What is the difference between them?
Should i get one or both?
Does it last forever or it expires affer a while...?

Both of them require to get renewed after a year(?), and Toriprime is necessary for VIP. Toriprime gives you access to the toriprime board which is kinda like wibbles. TP also gives you a larger signature and avatar, and the possibility for a sig pic. All of these get bigger with VIP

VIP expires after 6 month iirc. it also has more features such as animated and larger file sizes for avatars and bigger signatures.
Rest of the above is correct.

Well the whole list of stuff you can get is right here: http://forum.toribash.com/showthread.php?t=465052

That's really everything you can get.

What exactly is on the VIP special board? im too poor to buy VIP/TP

Vip gives you a background, a biggest profile pic, the availability to make him gif. You can also include a biggest signature pic.
You can also choose a symbol under your name.

Both toriprime and vip gives you an access to a private board.

*With VIP, globals costs 5k instead of 10k

Stone already gave the full list, only thing that's missing is that tori prime allows you to see an item's owners, I'll add that to the page later.

And the vip board is just wibbles2.0

Closing