I deal with a LOT of document change work
While not free, Beyond Compare certainly is the best I've come across and they have a free 30 day trial.
Beyond Compare: http://www.scootersoftware.com/index.php
Among some of the more notable features is the 'Specialized Viewers', e.g. comparing delimited data files cell-by-cell, binary content (byte-by-byte), mp3 tag info, various image files, i.e. image.jpg <=> image.gif, etc...
Specialized Viewers: http://www.scootersoftware.com/moreinfo ... fo_viewers
You can register shell extensions (32bit and 64bit); left-click file/folder (choose left side), left-click 2nd file/folder (compare to left); if both files/folders are in the same directory, then 2nd left-click ("Compare")
Give it a shot, you won't be disappointed and you have nothing to lose.
Oh, and it's fully portable: http://www.scootersoftware.com/support. ... ablemedia3