Two .doc, .docx or similar files can be compared in free LibreOffice Calc. Microsoft Excel no longer has this capability built in, despite early 2010’s versions of Excel having this capability.
LibreOffice Calc can compare untracked .xls, xlsx or similar spreadsheet files:
- open newer file
- Edit → Track Changes → Compare Document
- A convenient GUI opens that allows quick choice of desired changes in a list form.