please i need your help....plezzzzzzzz

[Romeo26222]

hello every body
i have a strange problem...i have a cd writer and i have a cd copy of a play station game
it is "wwf smakedown 2" and now i inserted the cd on my cd rom and go to the explorer to get the properies
of the cd and its size i found it is 619 MB but when i select all files on this cd and get its properties i found the
size is 691 MB !!!!!!
that makes me crazy because i can't make another copy of this game cd
so what is causing this problem and how the size of the cd is changed from case to another
note:i copied all the files to my ard drive and i found it 691 MB too!!!
thanx