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.
Straight bourbon whiskey is a type of whiskey (of course). Whiskey is a type of alcoholic drink made from cereal grains, distilled to strong spirit strength, and usually aged in barrels. Bourbon is a very specific type of whiskey. It must be made in the US. The grain used must be at least 51% corn (maize).