You are working with Excel files regularly - there will be a moment when you need to find a difference between files you are working with.
If your files are relatively small - you can sort the data, tile your worksheets one versus one on the screen and highlight the differences with Conditional Formatting feature. Easy work.
Excel table with 1000+ rows, that has inserted, and deleted rows and possible mixed order, can't be compared with cell-by-cell method described above.
Comparison algorithm become much more complex.