Using ISObuster to EXTRACT dvd....

I have a question...I use isoBuster to extract a full game (Disgaea) and the size came out about 800mb...I did the same to Goblin Commander and the size came out about 600mb...

but the problem is that these two games, if rip in ISO, would be about 1.2gig each....so why are the size different....I haven't test the ISO yet but the extracted one works...

I use CDvdgen to compile both game and they work....so what's all the extra stuff that I didn't extract...??:crazy: