Usually hillbillies have few or no teeth and some of them have lower education skills and live on the hills. Not all hillbilly live in the hills, there is some hillbillies live in the west, east as they have in their 'blood' from previous generations or relatives. They make and drink moonshine.
Rednecks have more than few teeth, some has no teeth, and often make homemade stuffs on their own. Some graduate high school, some not.
Redneck and hillbilly (varies on individuals) have different personalities. They love to drink beers, watch sports. Have junk cars and work on them.
Both use slangs, have own culture, pride, and some do play music. Some do have Confederate symbol (already discussed in another thread).