OOC:
As a non-alcoholic drink type person this is my understanding. Basically the "hard liquor" is more flammable. Vodka being generally over 100 proof, over 50%, alcohol is one of the more volatile. While beer, ale, mead, and wine have some it isn't considered much.
As an alchemist it would be known that oil based materials are best. Naphtha is a historical term used to apply to most of these fluids. There are some variations that burn hotter, are very sticky, more explosive, etc. Ex recipe: mix tar, oil, fat, crushed linseed, and stir in rough help fiber, place in clay/glass/wax sealed cask container = sticky fire bomb that burns for 3 rounds(vial) or 1 minute(mug sized jar) or 10 minutes(large jar or small cask)