Ok, here goes.
MBP has an SD slot and firewire ports. Also has the backlit keyboard and is upgradable to 8 gigs of RAM. It suffers from having a smaller hard drive, however that can be upgraded for an extra fee. It also, obviously has the tougher aluminum unibody design, as opposed to the weaker polycarbonate unibody design. This is a plus and a minus, as wireless signals apparently work better through the plastic body, however, the aluminum is far more durable (plus, it just looks so pimp).
Other than that, they are essentially the same machine. If the aluminum body doesn't matter, and you're not going to do any hardcore computing, and don't need those extra slots, I'd suggest saving the money and going with the white unibody. Otherwise, I'd go pro.