If a Video game is made for PC how does it change on a PS3

A game console, like the PS3 is actually a computer. XBOX 360 is also just like a computer. In the sense that they both have hardrives, they both download the media from the disc, so it can be played, used, or anything else a disc would be used for. So the video game I am assuming is a disc right? Then The PS3 can read the information on it just like a computer would :)