How to Compare Two Versions of a Document
Short answer
In Word, go to Review → Compare → Compare, pick the original and the revised file, and Word produces a third document showing every insertion and deletion as tracked changes. Google Docs does the same under Tools → Compare documents. Neither modifies your original files, and both handle the case where nobody remembered to turn on Track Changes.
On this page
Two drafts, nobody turned on Track Changes, and somewhere in nine pages something was altered. Reading them side by side is both slow and unreliable — the eye slides straight past a changed number.
Every mainstream word processor has a comparison function built in and most people have never opened it. It takes about fifteen seconds and finds everything, including the single-character changes you would never spot.
Pick the right tool for what you have
| What you have | Use | Notes |
|---|---|---|
Two .docx files |
Word → Review → Compare | Best fidelity, handles formatting |
| Two Google Docs | Tools → Compare documents | Needs both in Drive |
| One file with version history | Version history, not Compare | Already structured as versions |
| Two PDFs | Acrobat Pro, or convert first | Expect some noise |
| Plain text or code | A diff tool | Far better suited to it |
The third row is the one worth noticing. If both versions are actually the same file at different points in time, version history already knows what changed and is more reliable than comparing exports of it.
Word: Review → Compare
- Open Word. You do not need either document open.
- Go to Review → Compare → Compare.
- Set Original document to the older version and Revised document to the newer one. Getting these the wrong way round inverts every insertion and deletion, which is confusing rather than harmful.
- Under Label changes with, type something meaningful. This is the author name attached to every change in the result.
- Click More to open the options, then OK.
Word opens a new document with every difference marked as a tracked change. The original files are not modified.
The options worth changing
The expanded panel has a list of tickboxes controlling what counts as a change. Two matter:
- Formatting. Leave this on if layout matters, turn it off if you only care about words. A document that has been through a format conversion will otherwise report hundreds of formatting changes that nobody made.
- Show changes at: Word level / Character level. Word level is more readable. Character level is right when you are checking numbers, reference codes or anything where a single digit matters.
Under Show changes in, choosing New document is almost always what you want. The alternatives write the result into one of your two inputs.
Reading the result
The comparison document has three panes: the result in the middle, and the two source documents in a split pane on the right. Scrolling is synchronised, so you can see the same passage in all three.
If the panes are not showing, Review → Compare → Show Source Documents → Show Both.
The Reviewing Pane, also on the Review tab, lists every change as a scrollable list with counts. For a long document this is faster than scrolling the body, and the count at the top tells you immediately whether you are dealing with four changes or four hundred.
Accept and reject work exactly as they do with normal tracked changes, so the comparison document can become your final version if you want it to.
Compare versus Combine
Compare handles two documents. Combine handles the situation where you sent one document to three people and got three back, merging all of their revisions into one file with each person’s changes attributed to them. Run it repeatedly, adding one reviewer’s copy each time.
Combine keeps existing tracked changes; Compare assumes both inputs are clean and treats any existing tracked changes as content.
Google Docs
- Open the newer version.
- Tools → Compare documents.
- Choose the older version from your Drive.
- Set the attribution name and click Compare.
Google creates a new document in your Drive with the differences as suggestions. It is slower than Word’s version on long documents and less configurable, but it handles the common case well and needs nothing installed.
Both files must be native Google Docs, not .docx files sitting in Drive. If
yours are Word files, open each one and use File → Save as Google Docs
first, accepting that the conversion itself may introduce formatting
differences the comparison will then report.
When version history is the better answer
If the two versions are the same file over time, skip comparison entirely.
- OneDrive and SharePoint: right-click the file → Version history, or in Word, File → Info → Version History. Each version can be opened and compared against the current one directly.
- Google Docs: File → Version history → See version history. Turn on Show changes in the right panel and the differences are highlighted inline, which is better than anything Compare produces.
Version history is more trustworthy because it records what actually happened rather than inferring it. Our guide to getting back an older version of a file covers the recovery side of this.
PDFs and other formats
Word’s Compare needs editable documents, so PDFs need a detour.
Converting both PDFs to Word and comparing those works for text-heavy documents. It generates noise — PDF-to-Word conversion makes layout decisions, and two conversions make them slightly differently, so you will see formatting changes that exist only in the conversion. Turn the Formatting option off and read only the text differences.
Acrobat Pro has a native compare that is genuinely good and genuinely not free. Various web services offer PDF comparison; treat them exactly as you would any upload, which means not for contracts, payslips or anything containing other people’s data.
For plain text, CSV, configuration files or code, a proper diff tool is far better than a word processor. The comparison is line-based and exact, with no interpretation layer in between.
What to expect
On two drafts of a normal document, Compare finds everything in under a minute and the result is immediately readable. The common failure is not the tool but the inputs: comparing a document against a reformatted copy of itself produces hundreds of changes and buries the four that matter.
If that happens, turn off formatting comparison and run it again. If it is still unusable, the two documents have diverged too far structurally for a mechanical comparison to help, and reading them is genuinely the remaining option.
The real fix is upstream. Turning on Track Changes before sending a document out, or keeping it in OneDrive or Google Drive where version history runs automatically, means you never need to reconstruct what changed. Comparison is a recovery tool for a process that went wrong earlier.