BIN files larger than burn???

[sfbulldogs]

I have been backing up some PS2 CDs while waiting to get my Magic chip 2 installed. I have no way to test the burns to see if they are good. I am concerned since the BIN files I created with CDRWIN are significantly larger than the data on the end result burned CD. For example "Way of the Samuri" had a BIN file size of 569mb, but once I burned the CD it shows 495mb total???? Thanks for any clarification.