The basic difference between whisky, brandy, and rum is in their make-up, i.e. What they are made of. Whisky is made specifically from grain mash. The grain mash is generally fermented and then the fermented product is allowed to mature by having them stored in wooden containers or casks. The mash can be obtained from any of the available kinds of grain. It could me maize, it could be barley, or even wheat. Whisky can be of different types – Scotch, malt, grain, etc. Brandy is not grain based. It is made from grape wine, and also from fruit juice. In fact, most of the quality brandies available nowadays are made from grape wine. The key process again is fermentation, and the process as a whole is called double distillation. Because brandy is made from wine, which already contains alcohol, it has a high content of ethyl alcohol. A brandy can be allowed to mature, or you can also have it without letting it mature. This is another area where it is different from the other two drinks. Cognac is a kind of brandy. It gets its name because it was initially brewed in Cognac, in France. Rum, on the other hand, is made out of sugar cane. Specifically, it is made from the molasses derived from sugar cane. You can also make it from sugar cane juice. The processes involved in making rum are fermentation, and also distillation, after which the rum is allowed to mature. There are different types of rums as well.