What’s The Difference Between Whiskey, Bourbon, Scotch, and Rye?

Brown spirits. I love it, you probably love it, but my wife thinks it “tastes like burning”. Which is fine, more for me. The question today is, since all of these liquors look pretty much the same what makes one a Bourbon and one a Scotch?


Who Defines These Things?

A common set of definitions is important to make sure that you know exactly what you’re getting. Here in the United States, the typical spirit varieties are defined in 27 CFR 5.22, but other countries may have their own specific definitions (for example, “champagne” means very different things in France compared to the United States).

For most of the common types of spirits the definitions are pretty well consistent and agreed upon, but in some cases there’s some funky differences and debates going on behind the scenes.

Whiskey (or “Whisky”)

All of the spirits we’ll talk about today are technically a type of “whiskey.” Think of it like a branch of an evolutionary tree in biology — they all start from the same place, but different characteristics make for different kinds of spirits. Like how a beagle and a greyhound are both dogs, but very different kinds of dogs.

Most of the common terms and processes are pretty well established and agreed upon, but there’s still some slight differentiation on the spelling of “whiskey.” Whether or not there’s an “e” in the word really boils down to whether the country (or the specific distillery) is paying homage to the Scottish heritage, which is a region that drops the “e” and leaves it just “whisky.” A good rule of thumb for remembering which countries prefer which versions of the spelling is that the “e” only appears in countries where there’s also an “e” in the name.

America? Whiskey. Scotland? Whisky. Ireland? Whiskey. Japan? Whisky. I think you see the pattern here.

In practice, it makes no difference what you call it. The general process is all the same.

Whiskey is typically a grain based spirit, meaning that the source material for that alcohol are grains such as barley, wheat, corn, and rye. The first step of the process is to take the starchy contents of those grains, cooking them to break down the starch into sugar that is easily consumed by the yeast in coming steps. Usually this process involves crushing or “milling” the grains into smaller components and then cooking them in a massive vat for a period of time.

Single Malt” whiskey means that 100% of the grain used in the whiskey is barley, typically of a single variety. That barley is “malted” which means instead of being cooked to convert its starch into sugar it is soaked in water and allowed to germinate, a process which releases enzymes that naturally converts the starch in the grain into useful sugars. The germination process is halted by heating the barley when it reaches the right point in the process.

American whiskey and other un-specified whiskey can use multiple kinds of grains or combinations of different kinds of grains that are cooked together to turn the starch in the grains into sugar.

Once that’s complete, yeast is added to the sugary mixture. This microscopic helper eats the sugar within the mixture and produces heat, carbon dioxide, and (most importantly) alcohol. This is also the same process through which brewers create beer, which is why this slightly alcoholic slurry is called “distiller’s beer”.

At this point the alcohol content is somewhere between 7% and 10%, not nearly enough for whiskey. The next step is to concentrate the alcohol content through a process called “distillation”. Different elements evaporate at different temperatures, and (thankfully for us) alcohol evaporates at a lower temperature than water. So the goal is to heat the mixture, monitor the temperature, and selectively capture the concentrated alcohol vapors that are coming off the still. There are two typical options for how that happens.

The traditional method is to use a pot still, which is where a portion of that distiller’s beer is added to a large copper pot with a tall, skinny neck. This process is relatively slow and requires multiple trips through the still to create a high enough level of alcohol content, but also typically provides a more flavorful spirit at the end.

The more modern process uses a “column still” or “continuous still,” sometimes referred to as a “Coffey still” after its inventor. This industrial sized version is essentially a stacked series of pot stills, which continuously condenses and re-vaporizes the spirit at each level, distilling the spirit to higher and higher levels as the liquid moves up through the column. These stills can run continuously (hence the name), and produce mass quantities of spirit, but typically with less flavor.

At this point the alcohol is as white as Christmas snow and pretty tasteless. This is often referred to as “white dog” or “white lightning” whiskey. Some companies market this as “moonshine” but technically that would mean the whiskey was illegally produced. So unless you got your spirits out of the back of a truck from a man with suspiciously few teeth then you’ve probably just got un-aged whiskey.

To give whiskey its distinctive caramel color and improve the flavoring, the alcohol is sealed in casks (usually white oak, but sometimes stainless steel with some wood or other flavoring suspended inside) for a long period of time outside in the elements. This exposure to changes in heat and humidity force the spirit into the wood and extract some of the flavor and color into the liquid.

After some period of time the newly produced whiskey is removed form the barrel, sometimes mixed with water to reduce the potency, and bottled for distribution. Bottles which are not diluted with water before packaging are called “cask strength” because it’s exactly how the alcohol came out of the cask.

A version called “straight whiskey” is a legal distinction codified by congress which requires the use of charred new oak barrels in the aging process, and requires that the whiskey be aged a minimum of two years before being bottled. There’s also some specifics about alcohol content at different stages of the process, but that’s way too technical and boring and this isn’t the Wikipedia article.

Single barrel” whiskey, as the name suggests, means that all of the whiskey in the bottle came from just a single barrel. “Small batch” is a rather worthless distinction because there’s no specific requirements — “small” is a relative word — but it typically indicates that while the whiskey may be a combination of different barrels, all of it was distilled in a single run. “Blended” whiskeys can come from many different barrels and even different distilleries based on the bottler’s preference to create a specific aroma and taste.

Every spirit that’s produced along those guidelines can be called a “whiskey”, and some are happy with that simple designation. There are some delicious whiskeys in the world, but for those looking to ensure they get a very specific taste in their alcohol might want to investigate one of the sub-species of whiskey.


Scotch Whisky

Typically, “scotch” is a whiskey that is produced in Scotland according to a set of guidelines set forth by the Scotch Whisky Association. The main points of those guidelines are that all scotch must be:

  • Made in Scotland, on site at the listed distillery
  • Matured in oak casks for no less than three years
  • Containing no added substances (other than water and caramel coloring)
  • Labeled with an age that represents the youngest drop of alcohol in the bottle

That last part is particularly interesting. For distilleries that produce blended scotch whiskeys, they can use any vintage of distilled spirit they want (such as a little bit of a 50 year old batch for flavoring) but if even a single drop of 3 year old alcohol makes it into the bottle then it must be labeled as a 3 year old scotch.

Blended Scotch Whisky can come from a number of different distilleries, and use a number of different processes that are all combined to create a single bottle of spirits. Blended whisky might actually be the most traditional variety of scotch, as this practice dates back to the beginning of legal whisky in Scotland where distributors would buy batches of spirits from different distilleries and blend them together to make unique flavors that they sold under their own brand name. As an example, that’s exactly how Johnnie Walker started: as a spirit merchant’s blend of different sourced whiskey.

Single Malt Scotch Whisky is required to use the same rules as a “single malt” from above, with the added twist that the drying process in Scotland traditionally uses peat fired ovens to dry the malted barley. This peat fired smoke adds the unique aromas to the spirit that are often attributed to scotch. The spirit is also legally required to come from a single distillery, be distilled and aged on-site, and aged for three years in oak barrels before bottling. That doesn’t necessarily mean that all of the whisky in the bottle came from a single barrel, or even a single distillation run — blending different ages to produce the right flavors is a common practice — but it all came from a single place.

With a scotch whiskey you’ll typically see lighter flavors than other whiskeys, sometimes even a fruity taste, and most times a hint of peat (a flammable bog byproduct often used as fuel in fires to dry and heat the grains before distillation). The relatively cold and steady climate in Scotland means that it needs that time in the barrel (3 years) to develop the flavors and coloring, otherwise it might just be too bland.

Rye Whiskey

Usually associated with Canada due to its popularity in that country, a “rye” whiskey is defined as having rye make up 51% or more of the grains that went into the initial mash. That’s pretty much it. After that qualifying factor, it’s the wild west.


Contrary to popular belief bourbon doesn’t need to be made in Bourbon County, Kentucky. In fact, my favorite bourbon of the moment is produced just outside Austin, Texas. Any whiskey can be called a “bourbon” if it meets the following criteria:

  • Produced in the United States
  • Made from a mixture of grains that is at least 51% corn
  • Aged in new production charred oak barrels

Surprisingly, there is no aging requirement to be called a “bourbon.” However, the designation “Straight Bourbon” means that the alcohol has been aged in the barrel for a minimum of two years. But there’s a slight twist — if the whiskey has been aged less than four years, the label has to tell you exactly how long it was in the barrel. So if there’s no age statement on a straight whiskey, then it is aged at least four years.

What makes bourbon different from almost every other whiskey is the required use of a brand new charred oak barrel for each and every run. This ensures that the maximum amount of flavor from the barrel is imparted into the spirits, typically producing a darker color and a smokey flavor that isn’t seen in scotch, and the use of corn as the primary basis of the mash means that it has a sweeter flavor to offset that otherwise overpowering taste. In my mind, it’s the perfect balance of boldness and smoothness and my go-to kind of whiskey.

Interestingly, American bourbon barrels typically have a long life (despite being used for bourbon only once). Once they live out their purpose for making bourbon the barrels have a second (and third, and fourth…) life aging everything from Canadian Rye to Single Malt Scotch Whisky. Glenmorangie specifically uses former Jack Daniel’s barrels for their aging process.

Speaking of Jack Daniel’s…

Tennessee Whiskey

The United States has very few appellations of spirits and Tennessee Whiskey is one of them.

In this case, you need to start with a bourbon whiskey produced in the state of Tennessee (so already we know it comes from a grain bill the majority of which was corn). From there the whiskey needs to be filtered using the “Lincoln County Process” which involves filtering the whiskey through charcoal prior to being placed in new charred oak barrels. A minimum of two years later the whiskey emerges as Tennessee Straight Bourbon Whiskey.

Appellation Stacking

The use of a single one of these identifiers doesn’t necessarily exclude the others. So technically, you can have a “Small Batch Straight Bourbon Whiskey.” But some of them are mutually exclusive — a cask strength straight whiskey, for example, isn’t possible because the cask strength alcohol content is beyond the acceptable range of a straight whiskey. Similarly you’ll never see a single malt bourbon, because bourbon needs a majority of corn in the grain bill.

Either way, it’s always the strange edge cases that seem to make the most interesting flavors.

And with that, we conclude today’s lesson. Hopefully, you learned at least one new thing from this. And if not, congratulations on already being an awesome whiskey genius. Either way, go pour yourself a drink.



  1. The MOST straight-forward explanation EVER. So, Lincoln County Process aside, Bourbon is almost as casual a label as Whiskey. Outstanding read and great update, thank you.

  2. Loved this!!! So filled with info. Whiskey tasting Friday night will be delicious and informative:)!!

  3. As a long time sipper of Old No. 7, I have branched out into various bourbons and whisk(e)ys in that last couple years. After much research and in particular, the reading of this article, I now enjoy a variety of good bourbons and the occasional Scotch or whiskey. Well written in layman’s terms. Thanks.

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