That compare in word is pretty smart. You can insert a few lines and it knows
how to pick up with the comparison.
There's no built in option like this inside of excel. But Myrna Larson and and
Bill Manville wrote a macro that compares two worksheets cell by cell (a1 with
a1, z92 with z92).
http://www.cpearson.com/excel/whatsnew.htm
look for compare.xla
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Depending on what you're doing, this might work too.
Save each worksheet (you're really comparing two different worksheets) as .csv
files. These files are plain text.
You could use MSWord's compare to help find the differences in values.
It may help, but it's not quite the same.