Let me reword that so you get what your saying. "Can my PS3 games play on my PS2?" Get where I'm going? While a PSP game can be played on the Vita, a Vita game can not be played on a PSP as the PSP doesn't have the processing power to do so. Old game to new system, it works. New game to old system, does not work. Just helping you understand it abit.
Also, PS3 controllers cant be used on a PS2, DVD's cant be played in a VHS player, and square shapes dont fit in round holes. Mind blowing, isnt it.