The many different styles of bourbon can be confusing to the average drinker, but the term "single barrel" is self-explanatory and refers to bourbon aged in a single kind of barrel or cask. "Small batch" also seems like a fairly simple term, but small batch bourbon isn't necessarily made in literal small batches.

To make single barrel bourbon, distillers handpick a single vessel that has performed superbly and age bourbon in that vessel, then bottle the final product unadulterated. Meanwhile, the term "small batch" has little to do with how much bourbon is made per batch and more to do with the "small" number of barrels used to make the spirit.

Small batch bourbon is made using a blend of barrels, which is what sets it apart from single barrel bourbon. Only a handful of barrels are carefully chosen to make small batch bourbon, so it tends to be more expensive, but the exact amount of barrels used in a batch is rarely listed on the bottle, making the term a bit vague.