Two similarly named Word files are not necessarily identical. Document comparison displays differences as tracked changes in a third file. This guide covers Word desktop for Windows, particularly Microsoft 365; web and other platforms can differ.
Preserve the correct source files
Keep unchanged copies of both files in a separate folder. Record their origin, date and the confirmed baseline. A newer modification date does not prove a file is the approved version. Never work directly on the only contract or project copy.
Select the older or agreed baseline as the original and the version to review as the revised document. Reversing them reverses the meaning of insertions and deletions. To bring together contributions from several reviewers, use the separate Combine workflow, not this two-file comparison.
Explicitly compare into a new document
- Open Word and choose Review → Compare → Compare.
- Select the baseline under Original document and the second file under Revised document. Check the complete file paths.
- Open the extended options, usually with More. Deliberately choose whether to include formatting, comments and text changes.
- Select word or character level. Character level can help with individual digits and spellings, but provides more detail.
- Explicitly set Show changes in to New document, then select OK. Displaying the result in the original or revised document would modify that selected file.
Account for existing tracked changes
If a source already contains tracked changes, Word displays a prompt. Do not confirm without reading it: existing revisions are processed for the comparison; Microsoft specifically describes original-document changes being accepted in the comparison result. The result is therefore not an unchanged history of all previous edits. If the approval state is uncertain, cancel and clarify the baseline first. Your preserved source copies remain the reference.
Review the result and save separately
Under Review, display All Markup and, if useful, the Reviewing Pane. Examine changes individually. Check numbers, names, deadlines, tables, headers and footers directly against the sources. Hidden markup is not automatically accepted or removed; display settings alone do not decide the content.
Do not accept every change just to obtain a clean view. Save the comparison with a clear new name, for example “Project_Comparison_Baseline-vs-Review.docx”. Reopen it and confirm the markup is present. Save any later approved reading copy separately. Technical comparison supports review but replaces neither substantive approval nor preservation of the source files.