Oh here's what the one with the venom cover has (taken from wikipedia.org):
"There is a limited edition exclusive to the Playstation 2, which contains four character biographies (Ultimate Spider-Man, Ultimate Venom, Ultimate Carnage, and Ultimate Beetle), an interview with Stan Lee, a G4 special entitled "Making of Ultimate Spider-Man", Developer tips and tricks, and a special edition (also called "Activision Edition") Ultimate Spider-Man comic book containing scenes from issues 33-39. The limited edition version comes in a different case sporting plain purple and red holographic sides. (With a Venom symbol and Spider-Man symbol on each, respectively.) The case also comes with a cardboard sleeve with a picture of Venom on it. The DVD surface itself has a new picture on it purple instead of red once again with Venom, the instruction manual matches this trend with the cover being a fight scene between the two. The limited edition features are accessed from a new menu titled 'Limited Edition' via the unlockables screen."