ExamDiff - The freeware visual file compare tool. Guiffy is a visual file compare, diff merge and folder compare tool for MacOSX Guiffy SureMerge is. It offers a quick, intuitive, and powerful way to keep your files in sync. The diff command is available by default on the Mac, and it works the same in Linux and other unix operating systems as well, just in care you were wondering, and for Windows users it’s quite similar to how the ‘fc’ file compare tool works. ExamDiff is a freeware Windows tool to visually compare text files.Like Araxis Merge and DeltaWalker, it goes beyond (pun intended) comparing simple text and also allows diffing Word and PDF contents. Originally a product for Microsoft Windows, the Beyond Compare team has contributed a fine diff tool to the Mac platform. It includes links to each product, and the current price since last edit in USD. If you have multiple sheets in two different Excel files, your best option is to use a third-party add-on like Spreadsheet Compare.
The option you use to compare data in Excel depends on the volume of data and where its stored.
This is an aggregation of the answers posted on SO's deleted clone, Graphical diff for Mac OS X. Options Make It Easier to Compare Two Excel Files.