New user confusion about FFS behavior

[tktodd]

I just compared file content in two directories across two PCs which should have the same content as the PCs have historically been used as backup for each other. FFS shows 800 files as having different content ... mostly MP3s, JPGs and MOVs. FFS has them marked as "do nothing" which in fact may be appropriate as when I open them in either PC's directory, the file seems fine. Many of the files have different sizes. Some are the same. Any help on why these files have different content and what FFS is telling me would be appreciated.