Got a simple dc question I'm sure a lot of you can answer.

Hi! I will probably sound stupid asking this but I haven't found a clear answer.

Well the question is that if dc games are written on Giga disk then the games that are downloaded from the net are they complete or are some parts taken out since only 80 min cd-r's are used which only hold 700 MB? I would really appreciate a simple explanation thanks a lot for reading and for any replies.