From a local, welcome! Locals (& lifers) will almost always assume you are a transplant or out-of-towner if you use Raleigh-Durham to mean the area. The metro area is called the Research Triangle Park, RTP, or Triangle. Raleigh-Durham is only the airport; calling it RDU is fine, too. Raleigh ("Rolly") & Durham ("Durm") have very distinct identities & do not like to be conflated w/one another. If you live in a suburb, folks will say either its name (town, county, etc.) or of which city.