The process for making Whisk(e)y entails distilling from a malted grain: rye, corn or barley. Whisk(e)y for me is a lot like beer in that both are made from many similar ingredients – grain, water and yeast – so really beer is basically un-distilled whisk(e)y. The variation of grains, proportions and methods employed in making whisk(e)y, as well as the maturation and distilling, the type of wood, barrel and aging all play a significant role in making each product distinct.
Bourbon is 51% corn by law and usually contains 70% to 90% corn, rye, barley or wheat in the mash bill, and must be aged in new American white oak barrels for a two-year minimum. A defining characteristic of bourbon is wood. You can taste it.
Rye is a mash bill of no less than 51% rye (of course), some corn, and or barley. Like bourbon, Rye also must go through a two-year minimum aging process in American new charred oak barrels. A defining characteristic for rye is spice, which can come from the char found in the barrels.