you should try this free online tool - www.cloudyexcel.com/compare-excel/

works good for most of the time, sometimes the results are a little off.

plus it also gives a good visual output

http://i.stack.imgur.com/7L3gB.png

You can also download the results in excel format. (you need to signup for that)

compare files- is very powerful and , as you will see in this tip, is very easy to use. To compare two excel workbooks, begin by opening the workbooks. Then, choose compare files from the inquire tab of the ribbon and select the two workbooks you want to compare.