Downloadable PSP games can in most cases be played on PlayStation Vita, and with improvements too. Twitter user ReKnights snapped a pic showing Final Fantasy Type-0 on the two systems.
A couple of points: ReKnights did not say what settings he used for the Vita version. Also, he took the picture with his cell phone camera.
Another early PS Vita adopter posted some comparison pics of Monster Hunter Portable 3rd. In these shots, the Vita version is set with binary filtering on.
4Gamer also did somewhat of a comparison of Type-0 on Vita and PSP. Instead of showing how the game's visuals change, 4Gamer tried to move their PSP Type-0 save file over to Vita after installing the Vita management app on their PC. You can read their exploits (in Japanese) here.