Compare two Excel sheets

You might be able to use VLOOKUP depending on how complex your key structure is.

(Do a search on the Microsoft Office Support website for VLOOKUP.)

You can covert it .csv and there are lots of options

If you have access to Unix you can run diff <file1> <file2> or sdiff <file1> <file2>

If you have access to TortoiseSVN or TortoiseGit or Eclipse, you can diff those two files and the differences will be done on screen. For Tortoise select the two files and click Diff. For eclipse drag those two files into the gui, select and choose diff

If the files are not very big try - http://neil.fraser.name/software/diff_match_patch/svn/trunk/demos/demo_diff.html You can put your text into the two boxes and run a diff using a proven diff algorithm [Myer's diff]

If you are Windows you can use WinDiff or WinMerge - http://winmerge.org/ . I personally use WinMerge as it can diff directories.

Hope this helps.