What's the Difference Between Scotch and Bourbon?

I’ve lost count of the number of times that I’ve heard some version of the following: “I love bourbon, but Scotch is just too smoky for me.” Or, the opposite side of that particular spirituous coin: “Bourbon is just too sweet for me, and way too strong. I really just stick with single malt.”

We have so much to unpack here!

There are, of course, significant differences between Scotch and bourbon, but generations’ worth of bad information and boozy stereotypes have resulted in a lot of misapprehensions about both.

To begin, both Scotch and bourbon are whisk(e)y, meaning they’re wood-aged spirits that have been distilled from a fermented mash of grains. In Scotland, barley is the dominant grain, and single malt Scotch whisky, for example, must be composed entirely of malted barley. Single malt Scotch is the product of a single distillery, as opposed to a blend of distillates or maturates from multiple distilleries. There are, it’s important to note, other regulations that guide the production of blended whisky, single grain, and more.

The whisky from each region of Scotland tends to boast its own unique character, often the result of some combination of terroir, climate, distilling tradition, and more. So while there are certainly plenty of smoky, peaty whiskies out there, not all single malt Scotch whisky is smoky.  Islay, far south in the Hebridean Islands off the west coast of the country, is home to producers like Laphroaig, Octomore, and Ardbeg. It’s the most famous region for this style, a result of the fact that the malted barley is dried using peat-fueled fires, the smoke of which dries the grain and imbues it with its characteristic peaty smoke. Yet there are also un-peated whiskies from Islay – Bruichladdich is a great example.

The whiskies from the Highlands and Speyside often tend in the opposite direction, with notes of orchard fruit, dried stone fruit, honey, heather, and occasionally even flowers coming to the fore. And on top of that, individual producers have their own styles, types of pot stills, water sources, and climates where their aging warehouses are located. 

Bourbon, on the other hand, is based on corn, not barley. According to regulations, it must be composed of a mash bill (basically the list of grains that have been used) consisting of at least 51% corn. Some brands use a lot more than that, but 51% is the legal minimum. Beyond that, rye, wheat, and barley are common supplements, though other grains may be used as well.

Once distilled to the required strength (no more than 160 proof, and barreled at a maximum of 125 proof), bourbon must be aged in charred new oak. While most brands use American oak barrels, the law actually doesn’t specify that the wood has to be from the United States. Any expressions that have aged for less than four years have to specify the amount of time they spent in barrel prior to bottling. Some brands finish their whiskeys in a secondary barrel (ex-Port, for example), but the primary aging must be in charred new oak.

In general, bourbon is a sweeter spirit than single malt Scotch, but just as it’s impossible to paint all single malt Scotches with a broad brush, the same goes for bourbon. A higher percentage of rye in the mash bill, for example, will bring a more spicy character to the equation, whereas more wheat tends to lend sweetness, softness, and a pleasantly plush textural component.

Then there is the issue of the barrels themselves, which are impacted not just by where the wood is sourced from, but also the type and level of char. Whereas warm vanilla notes are not uncommon in bourbon, some deeply and intensely charred barrels can lend a smoky hint to the whiskey inside.

Finally, there is the issue of spelling: In Scotland, whisky is spelled without an ‘e’ and rendered as ‘whiskies’ when referring to several. In the United States, Bourbon tends to be spelled with an ‘e’ and referred to as ‘whiskeys’ in the plural. But there are exceptions: Maker’s Mark, for example, uses whisky — no ‘e’ — on their label.

For all of their differences, however, single malt Scotch and bourbon are both unique and deeply expressive evocations of their respective places of origin. There’s room on the bar cart for both of them. Preferably several different bottles of each.