Help with bluray playback on ps3

Batman begins and the dark knight play at 1080p and dead mans shoes and this is england play at 1080i.Why cant i get them to play at 1080p.On the cases it says 1080p.Any ideas?
Answer #1
Check the Blu-Ray box, on the back it shud say whether its 720p/1080i/1080p. Its the same with games some r full-hd some not, etc.
Answer #2
there isnt much difference between 1080p and 1080i. you get the same number of pixels on screen, just they are drawn on the screen in a different order