You can plug it in to a HD tv. 
Can you do that on all psps? Because i have a phat and i read that it can only be done on the ones after the phat.
I'm pretty sure you can. I have a psp 3001 and I remember reading some indication on how to hook it up to a HD tv. I don't know why they would take away that feature.
The main difference I know of between the phats and the thins is that the phats are interlaced displays and the thins are progressive. Other than that the thin has a microphone and there the difference ends (except for size/weight of course).