There's a significant difference between the screen on the MBP and the MB, just as it was on the previous models. Unfortunately I do not have the specs of the screen, but it's better then the previous model afaik and better than most other laptops. And it's LED.
The display shouldn't be what made anyone buy a MBP instead of the MB. You can get a external display if you're not happy with it, which is probably a good move anyway since the laptop screens are to small for most people.
Oh and if you go with the MB, I'd pick the 2.0GHz one, 2.4 is only marginally faster. (About 9% overall, about 2-3% in games)