Usually the video card and video RAM is what makes games, and videos look better. RAM and CPU makes the game runs more smoothly. Blu-Ray is just used to carry the data to be translated into video with your CPU, Video card and other parts are responsible for.
Xbox 360 and PS3 versions look the same to me as well.
Coding/computer programming and graphic design also determine how good a video games graphics look.
God of War II for the PS2 looks great even when played back on the Playstation 2 which is much slower then the Xbox 360 and PS3 because GoW II had great computer programming and graphic design which used all the power of the PS2 to the fullest.