Acrobat DC lets one select what to display, you need to set the filter in the DC compare documents to display the same items as the older version. Changes in DC are indicated by a balloon comment.
Older versions of Acrobat report changes in positon as a difference. Make sure you are using the same parameters for the searching in the 2 programs.
Acrobat 7 is very old and no longer supported by newer OSs. If you are using Windows 7,8, or 10 you might consider upgrading.