Q: file creation date vs EXIF creation date

With iphone5c icloud "backups", what would cause image file creation date and EXIF creation date to be different?  In my backups I see some images where the file creation date is dated earlier than the EXIF creation date, AND some images where the file creation date is dated later than the EXIF creation date?  Is that even possible?

Thanks for the help,

Jv