You'll forgive me, then, for focussing on the things that are different. Because in some respects Fallout: New Vegas is a very different game from Fallout 3, and that's largely because it's better written. It understands that sometimes you must do awful things for a greater cause, or choose the best of two bad options. It offers you decisions all the time, but it rarely forces you to make any. It understands that morality is ambiguous, and subjective, and that games shoving obvious choices in your face undermines their emotional maturity.