This tool allows a simple comparison of two Excel Sheets or Workbooks. It not only compares values, but also allow to highlight formula differences.
Free • Proprietary
What is Excel Sheet Comparator?
Excel Sheet Comparator is cross platform (Windows, Mac OSX) tool that allows comparison of two excel files. It runs on Windows and Macintosh and it doesn't need installation.
Not only it helps identify the differences in values, but also in formulas, and then eases the process of merging the information.