playstation will play games and dvds but not bluray movies

hello my own question kind of confuses me, but my playstation will play all my games just fine (which i was under the impression that they were bluray discs) and will play standard dvds just fine but wont even register the disc in the drive when i try to play a bluray movie. this problem doesnt even make sense to me since the games and the bluray movies are the same type of disc. if anyone has an idea of why it is doing this or how to fix it i would be very appreciative.