Hypernyms (cordial is a kind of...): alcohol; alcoholic beverage; inebriant; intoxicant (a liquor or brew containing alcohol as the active agent) Hyponyms (each of the following is a kind of cordial): absinth; absinthe (strong green liqueur flavored with wormwood and anise) ratafee; ratafia (sweet liqueur made from wine and brandy flavored with plum or peach or apricot kernels and bitter almonds)
Bourbon is mostly made from corn, at least 51% corn. Rye whiskey is mostly or entirely made from Rye. They differ in many other details - for example Bourbon must be aged in new, charred American Oak barrels and made in the US, Scotch must be made in Scotland, but the big differences are the grains used.
In reality, the main difference surrounds the question of what they're made of: whiskeys are made from a fermented mash of grain (usually corn, rye, barley or wheat) whereas bourbon has to be comprised of at least 51% corn as part of its grain mash.