i went from a 15.4" to the macbooks 13.3' there was a little bit of getting use to the screen size but with app spaces i find that it very easy to use the 13.3" screen.

i think both are very reliable. you shouldnt have to worry about either of them.

photoshop may be faster in the mbp due to the dedicated video card.

the pro has a dedicated video card, express card bay, firewire 800, backlit keyboard, multi touch track pad, and a LED backlit display.

(EDIT)

I am guessing if you are looking at the mbp with the 160gb hard drive you are referring to the previous gen mbp. the previous gen doesn't have the multi touch track pad, and uses a different intel chip