Distillers can label a whiskey "barrel proof" if they do not dilute it with water before bottling. This means that the alcohol content of barrel-proof whiskey is higher than that of other types of whiskey. As a result, barrel-proof whiskey has a more intense flavor and is often considered higher quality.
There are two main types of barrel-proof whiskey: cask strength and single barrel. Producers make cask-strength whiskey from a blend of different barrels. On the other hand, distillers make single-barrel whiskey from a single barrel. Cask strength whiskey is typically more expensive than single barrel whiskey.
Barrel-proof whiskey is typically more expensive than other types of whiskey due to the higher quality of barrels used. As a result, barrel-proof whiskey has a more intense flavor and is often considered higher quality.