Aside from the obvious - that is, a larger chassis and high resolution screen - there are a couple of other features the MacBook Pro has over the MacBook. One is the inclusion of a FireWire port, presumable so as not to annoy those professional types who went out and bought FireWire-equipped video cameras knowing that data could easily accessed and edited on the last-generation of Pros.
The other feature the MacBook Pro sports which the MacBook doesn't is an ExpressCard slot. Once upon a time I would have praised such an addition, but in this day and age I'm pretty ambivalent as most of the additional functionality which used to be provided via the ExpressCard interface is now built into most laptops. And the only feature which often isn't, HSDPA, is now available in a much more convenient (not to mention universally compatible) USB form.
On the plus side, the illuminated keyboard which was an upgrade item on the MacBook, is standard on the Pro. Personally I am a big fan, although I still prefer the lighting method seen on ThinkPads - a downwards facing LED - as it can also be used for reading paper - perish the thought! The brightness of the LEDs under the MacBook Pro's keyboard is adjustable, too, either manually or automatically in relation to ambient light conditions. I'd leave that option turned off, though, as I find it frankly useless at setting a suitable level of illumination.
One aspect the MacBook Pro shares exactly with the MacBook is its keyboard. At first glance I was slightly puzzled by Apple's decision to use the same keyboard on its 15.4in system as on its 13.3in offering, but actually it makes sense. Not only does it save Apple a bit of money, by dint of not having two different keyboard production lines, but actually, the MacBook's keyboard is pretty damn good and making it any bigger would probably detract from, rather than benefit that.
As Andy commented, these new keyboards lack that reassuring 'click' on every keystroke that the previous generation have and, indeed, feel that bit spongier. Being used to my current laptop, a Sony VAIO TZ, which has a much more reassuring feedback when typing, I initially found this pretty disconcerting, but after a day or two with the Pro I got used to it. Doing a quick in-office survey the general reaction was ambivalence in either direction, so it's definitely a matter of personal preference. As ever, if you can try before you buy so much the better.
The multi-touch enabled touchpad is every bit as good here, too, as on the MacBook. Occasionally it seems a little too sensitive and when dragging the fact the pad has edges becomes painfully obvious with alarming frequency, but such niggles are soon dispelled by the sheer joy and ease of use that multi-touch brings to the party.