i've had both so i'll say what i know
-vBulletin costs $160 bucks US (or at least it did about 3 months ago when i last checked) wheras phpBB is free
-vBulletin is a LOT more flexable, you can do a lot more things with it
-phpBB is easier to setup
vBulletin has so many things that you would never learn them all 🙂
one of the cool things to attract members to a board is the points system vBulletin has. you can have it so a newly joined person gives the name of the person who told him about that board, the person who told the newly registered person about the board gets points. people with points can do things like have special titles under their name, get avatars (admins set how much things cost), have signatures. i'm not sure but i think you can set it so enabling private messages costs a certain amount of points as well. people can gain more points with high rated posts.
i better stop before i get too excited 😃
