Bourbon vs. Whiskey All bourbons are whiskeys, but not all whiskeys are bourbons. Bourbon is produced only in the United States, and according to US regulations, at least 51% is corn and must be produced from grain wort aged in new charred oak containers.
There is no minimum aging period for bourbon whiskey, but varieties aged less than four years must indicate age on the label. However, it needs to be aged for at least two years to be called straight bourbon.