This question comes up from time to time, so I thought I would address it. Bourbon and Corn Whiskey are both made from corn, so what's the difference (other than that bourbon is delicious and corn whiskey is usually rather foul)?
There are three key differences:
1. Barrels. Bourbon, as most of us know, must be stored in new, charred oak barrels (well, technically it doesn't have to be a barrel, but you know what I mean). Corn whiskey does not have to be barrel aged at all, but if it is, it can only be aged in (1) used oak barrels; or (2) new, uncharred oak barrels.
2. Corn Percentage. Bourbon must be made from a mast of at least 51% corn whereas corn whiskey must be made from a mash of at least 80% corn. So you can have a bourbon and corn whiskey that are the exact same mashbill (at least 80% corn), but they must be stored in different types of containers.
3. Taste. Bourbon is good. Corn whiskey sucks. (I actually couldn't find this listed in the regs, but I'm sure it's in there somewhere).