Bourbon is a type of whiskey, made with a mixture of grains containing at least 51 percent corn. Bourbon can be produced anywhere in the United States, not just Kentucky as is widely believed. The alcohol must be distilled to no stronger than 80% ABV, and the distillate must then enter charred new oak barrels at 62.5% ABV or less. Bottles can be labelled 'Straight Bourbon Whiskey' when they have aged in charred new oak for at least two years. Bourbon and whiskey are often compared directly against each other. In fact, bourbon is a type of whiskey, much like Cabernet Sauvignon is a type of wine or IPA is a type of beer. While bourbon is legally bound to be made using at least 51% corn in the mash, whiskey can be distilled from wheat, rye, barley, or corn. Whiskey’s distillation proof must be no more than 95% ABV and its origin can be anywhere in the world. 

The American's, like the Irish, spell whiskey with an 'e'.