[macworks]

You may see slightly different sizes of files/folders on different computers due to different hard drive capacities. A file that takes up x amount of space on one hard drive may not necessarily take up exactly the same amount on another drive. The reasons are highly technical in nature, so I won't go into it.

However, a difference of 10 GB likely means that files are missing. If you open iTunes on the Mac and go to the preferences, click on "Advanced", there is a check box that says "Copy files to iTunes Music folder when added to library". If this box is NOT checked when you import songs, those songs are not copied to the iTunes music folder. Instead they are left where they are whether that be another folder on your computer (like your desktop) or another hard drive.