Since Im here in NC and visit both often....
Charlotte is more of a metro, has the Panthers, downtown and feels like an actual city. You got Carowinds, the Panthers, Bobcats, Nascar, the mall, and the Galleria.
Raleigh is an overgrown college town. Traffic is horrible. Entertainment options aren't that bad for a city it's size for nightlife, restaurants, etc. but you're limited. Nice shopping areas and malls but overall not much to do during the day in my opinion. Durham is probably the jewel of this area though it has some hood spots some parts of Durham are really nice if you're going to settle down.
All in all, I'd probably pick Charlotte if I had to choose. The airport, sports options, regular concerts/events and the yearly CIAA events make it heads and shoulders the best city for someone who's not settled down.