How does the complete edition of L.A. Noire work?

I got it and there are 4 disks? When I play different disks, it looks like the same game?How does the complete edition of L.A. Noire work?
do you have it on pc or on xbox? on xbox it has different disks because each disk lets you play different parts of the game, because it has so good of graphics (in the cut-scenes) that each disk has little or no space on it. If on pc i am not sure, because i read on multiple site that it wasn't coming out on pc i bought it for xbox, though now it is out on pc cheaper than my xbox's copy was.