No they aren't all the same. When Call of Duty is made by Infinity Ward its immense, for them it's all about the game play it's silky smooth and truely is the best game on the market for gameplay, the downside are that the graphics are slightly dated with it, when treyarch make it they do a very bad job of it and it seems like it's thrown together. If you wanted to try and get into it then start with Modern Warfare 2, IMO it's by far the best game of the COD series. They are very much all the same on the whole as theres only so much you can do with FPS, another decent FPS is Battlefield, i don't like it as much as the COD series but it is defeinatley worth a play.