How to Compare Documents in Word: Track Changes, Revisions, and Version Differences

Microsoft Word's Compare feature is one of its most underused productivity tools. Whether you're reviewing a contract that went through multiple drafts, collaborating on a report, or checking whether someone changed your original document, Word can show you exactly what's different — line by line, word by word.

Here's how it works, what affects the results, and why your specific workflow matters more than any single setting.

What the Compare Feature Actually Does

When you compare two documents in Word, the software performs a legal blackline comparison — it treats one document as the original and one as the revised version, then generates a third document showing every insertion, deletion, moved text, and formatting change between the two.

This is different from simply reading both documents side by side. Word's comparison engine tracks changes automatically, even if neither document had Track Changes enabled when it was edited. The result is a marked-up document where additions appear underlined, deletions appear in strikethrough, and moved content is flagged separately.

How to Run a Document Comparison in Word 🔍

The steps are straightforward across modern versions of Word:

1. Open Microsoft Word (you don't need either document open first)
2. Go to the Review tab in the ribbon
3. Click Compare, then select Compare… from the dropdown
4. In the dialog box, set your Original document and Revised document using the file browser
5. Expand More to configure which types of changes to track (formatting, comments, tables, headers, etc.)
6. Click OK

Word generates a new comparison document. The original and revised files are not modified.

What Shows Up in the Result

The Reviewing Pane on the left (or bottom) gives a summary of all changes, which is especially useful in long documents with dense edits.

Compare vs. Combine: Understanding the Difference

Word offers two options under the Compare button: Compare and Combine. They look similar but serve different purposes.

Compare is for when you have two versions of the same document and want to see what changed. It's a read-only audit — useful for legal review, contract tracking, or quality control.

Combine is for when multiple reviewers have edited separate copies of the same original and you want to merge all their tracked changes into one document. This is the right tool for collaborative editing workflows where different people worked independently.

Choosing the wrong one won't damage your files, but it will produce a result that's harder to interpret.

Factors That Affect How Well Comparison Works

The Compare feature isn't magic — its accuracy and usefulness depend on several variables.

Document Format and Compatibility

Word's comparison engine works best with .docx files. Comparing a .doc file with a .docx file, or a document exported from Google Docs, can introduce formatting noise — changes that appear in the comparison result but are actually conversion artifacts rather than real edits.

If you're comparing a PDF converted to Word or a document that passed through multiple applications, expect more false positives in the diff output.

How Much the Documents Diverged

Word's comparison is optimized for documents that share a common base. If you're comparing two documents that started from the same template but evolved in very different directions — say, a first draft and a heavily restructured fifth draft — the comparison may flag large blocks as moved or deleted when the content was actually reorganized.

The more similar the structure, the cleaner the comparison result.

Formatting-Heavy Documents

Documents with complex formatting — tables, text boxes, tracked changes already embedded, or heavy use of styles — can produce cluttered comparison results. You can reduce this by unchecking Formatting in the comparison settings dialog if you only care about content changes, not visual ones.

Word Version and Platform

The Compare feature behaves consistently across Microsoft 365, Word 2019, and Word 2016 on Windows. The Mac version of Word has the same feature set, though some UI elements are slightly reorganized under the Review tab. Word for the web (the browser version) has a more limited implementation — it supports basic comparison but may not surface all change types that the desktop app catches.

If precision matters — for legal documents, compliance reviews, or editorial work — the desktop application generally gives more reliable and detailed output.

When Comparison Gets Complicated 🗂️

A few scenarios make comparison harder to interpret:

• Documents with comments: Word will flag comment insertions and deletions separately. If reviewers left comments in one version and not the other, those appear as changes even if the underlying text is identical.
• Auto-formatted or autocorrected content: Differences introduced by Word's own autocorrect or autoformat features can show up as changes even if no human edited that text.
• Scanned or OCR documents: Comparing documents that went through optical character recognition introduces character-level noise that isn't meaningful.
• Different authors editing in different apps: A document edited in LibreOffice, then compared in Word, may surface formatting differences caused by the application difference rather than intentional changes.

What the Settings Let You Control

In the Compare Documents dialog (under the More button), you can choose which elements Word looks for:

• Insertions and deletions
• Moves
• Comments
• Formatting
• Case changes
• White space
• Tables, headers, footers, footnotes, and fields

Narrowing these settings reduces clutter in the result and makes it easier to focus on what actually matters for your review. If you're auditing a contract for substantive text changes only, turning off formatting comparison is usually the right call.

Whose Setup Actually Determines the Outcome

The usefulness of a document comparison in Word depends on factors that vary by person and workflow: the file formats in play, how many rounds of editing occurred, whether the documents lived in a single application or bounced between platforms, and what level of detail the review actually requires.

Someone doing quick content checks on clean .docx drafts will have a very different experience than someone comparing documents that were edited in multiple tools, converted between formats, or touched by automated systems. The feature works the same way — how well it serves you depends entirely on what you're feeding it.