the macbook pro ships with displays from several different manufacturers: Samsung, LG, Chimei and AUO. There is quite a difference between the different models, and also between specific units by the same manufacturer. I've had all of them and I've also had a few Airs, and if I compare the best Air I've seen (a Chimei Screen) with the best MBP display I've seen (AUO before it inverted on me and had to be returned....), I think they're comparable. If I compare the worst MBP (Chimei) with the average MBA (not sure but the model number is most common one), the MBA was infinitely nicer in terms of color, brightness and lack of hues/viewing angle. So I really think it's a lottery and there's no way to generalize about the screens. I'd prefer a good MBP display over a good MBA screen because of the size, but I'd choose a good MBA screen over a bad MBP screen any day.
My two cents...