Create a 3rd workbook.
Copy each of the worksheets from the two workbooks into this 3rd workbook (it'll
be easier and safer).
Close the 2 original workbooks.
Add a new worksheet to this workbook.
Copy a header row and all the data from either of the worksheets into column A.
Copy the data (no header row) from the other worksheet under the data in column
A (of the new sheet).
Now you have all the keys (some duplicated) in column A.
The use data|Filter|advanced filter to get unique values from that single
column.
http://contextures.com/xladvfilter01.html#FilterUR
and
http://www.contextures.com/xlVideos04.html#AdvFilt2003
(Both from Debra Dalgleish's site)
Then use a bunch of =vlookup()'s or =index(match())'s to return the data to be
compared (two columns--one for each worksheet). And a third column that would
indicate the differences.
Debra Dalgleish has lots of notes on =vlookup() and =index(match()) here:
http://www.contextures.com/xlFunctions02.html (for =vlookup())
and
http://www.contextures.com/xlFunctions03.html (for =index(match()))
and
http://contextures.com/xlFunctions02.html#Trouble
Then you can retrieve the values that you want from each of the sheets--as long
as they fit on the worksheet.