I was looking through Wikipedia last night because I wanted to know what the difference is between all the different spirit drinks. This is the verdict...
Brandy is wine that has been distilled to make it more concentrated.
Whisky is wheat mash that has been distilled and aged in a barrel to add flavour.
Rum is sugar cane or sugar based alcohol that has been distilled like the others to remove water content and make it more concentrated.
Gin is made from berries and is also aged in barrels.
Vodca is made from potato starch alcohol and is distilled for longer or multiple times to make the alcohol content more high.
