I could easily see the differences between two versions of the same HTML file, and merge them any way I wanted to. Beyond Compare also has a feature for finding differences between image files.

If you have two similar Excel spreadsheets, or different versions of the same original spreadsheet, it can be useful to compare the Excel files and see how they differ. If the spreadsheets are ...

How to Compare Values of One Workbook to Another in Excel. In Microsoft Excel you can use a formula to compare two similar documents in different workbooks. For example, if a small business has ...

See: 10 Excel time-savers you might not know about (TechRepublic) Custom rules The two lists shown in Figure A are similar, but there are subtle differences. A few items are unique to both lists.