Final answer:
Tennessee whiskey differs from Bourbon in that it must undergo the Lincoln County Process, which involves filtering the spirit through sugar maple charcoal.
Step-by-step explanation:
The important aspect in which Tennessee whiskey differs from Bourbon, other than being produced in Tennessee, is that it must be filtered through ten feet of finely chopped charcoal produced by burning 'ricks' of sugar maple. This process is known as the Lincoln County Process and is a distinctive feature that sets Tennessee whiskey apart from other types of bourbon and whiskey. The other two options listed are not accurate; Tennessee whiskey can indeed be produced from a mash having more than 51% corn, and it does not have to be aged in previously used bourbon barrels; new charred oak barrels can be used.