Is there any reason why

when ripping material off of the same disc with the same settings with handbrake the movies would be different sizes? I was ripping my copy of season 1 of house and I ripped the first 4 episodes off of disc 1 with the same settings and the first episode came out 550 MB and in full screen mode has a substantial amount of black around all 4 sides. However, the other episodes on the same settings came out at about 300 MB and took up most of the scree in full screen mode. anyone have a possible explanation?