I recently bought the Game Of the Year edition Fallout 3 on Xbox 360 and i installed all the expantion given on disc number 2. A few monthes earlier i had installed the Broken Steel/Point Lookout disk and found that the file size of Point Lookout on the Game Of The Year edition is 413mb while Point Lookout on the Broken Steel/Point Lookout disk is 450mb large. I was wondering if there is any difference in the gameplay and why the size of the file is different?

I think that difference consists of the interface for the download and the installer itself.

No difference in game-play or content.