The pro should last longer, especially the hard drive because it's much cooler inside (because it's all dispersed through the case).
I've got a MacBook Pro (my own and only computer) and my dad has a MacBook, and they're both very good computers, but the MacBook Pro really is streets ahead in terms of usability and overall 'user comfort' (which makes a huge difference to how well you use it IMO).
Aluminium case - disperses heat
Larger hard drive bay - able to take 'thicker' drives
Better quality display - much more comfortable to look at than a MacBook display
Higher resolution display - more workspace
Ambient light sensor - really helps your eyes out, believe me.
Backlit keyboard - definitely not 'just a gadget', very good in low-light.
FireWire 800 connection
PC expansion slot
Better WiFi/BlueTooth range (in my experience)
Will last longer - less internal heat, whilst the MacBook kinda 'bottles' it in
Better iSight, if it means anything.
Better keyboard - much faster typing speed than the MacBook in my experience
MUCH better trackpad - the Pro's is so much smoother and overall nicer than the MacBook's.
Dual-Link DVI connection for running big displays
Feels much better made
Looks nicer (at least IMO)
If you can afford the Pro, get it, it's more than worth the extra cash. If not, the MacBook is the one for you...