The difference is that it's a "Pro" and it's awesome, unlike the Macbook which is not a "Pro" and ...well it's still a pretty awesome computer.
I went from my second gen white Macbook to a 13" Macbook Pro and the differences (aside from me going from my upgraded 3gig of RAM down to 2gig this one came with) are:
Macbook - Firewire 400
Pro - Firewire 800 (and I don't remember if the new Macbooks even have any firewire at all)
Macbook - no SD slot
Pro - SD slot
Macbook - both input and output audio jacks
Pro - only one jack for audio and you have to tell Mac OS how you're going to use it (kind of a step back, really)
Macbook - one button trackpad
Pro - no button trackpad that acts like an iPhone as well
Macbook - okay screen
Pro - awesome brilliant bright screen even if it's the same size
Macbook - Mini DVI
Pro - Mini-mini DVI
Macbook - 3-4 hour battery tops (removable, experienced value)
Pro - 6 hour battery or more (non-removable, also experienced value)
Macbook - keyboard I felt necessary to use external with all the time
Pro - it looks like the same, but somehow feels different. I still use a bluetooth external at home, but at work I can use the keyboard built-in. Can't explain why
Macbook - sexy
Pro - very very very sexy
Also the Macbook is reported (and experienced) to have outstanding WiFi pulling range, though I haven't noticed any issues with the Pro's WiFi.