How do you find the differences between two texts?

Your landlord has sent the "final version" of the tenancy agreement, or a classmate has shared the corrected draft of your group essay. At a glance the two texts look almost identical, but you do not want to sign or submit without knowing whether a figure, a date or a single word has changed. Laying two pages side by side and reading line by line is tiring and unreliable: the eye skims straight past a small change inside a familiar sentence.

There are several ways to hand this job to a computer, and the right one depends on the format of the files you have. Below we start with that choice, then show how each route works and which traps make the result misleading.

First, check the format of both versions

Before picking a tool, check whether both files are in the same format. If both are Word documents, Word itself gives the richest result. If both are PDFs, you need a PDF comparison. If one is Word and the other a PDF, bring both down to plain text first. If the text sits in an email or a message, you do not even need a file — copy and paste is enough. For JSON data such as a product feed or a settings file, the JSON Compare tool, which matches fields one by one, gives a more accurate answer.

The diagram sums up which route to take in each case.

Two Word documents: the Compare command

To compare in Word, you only need to open one of the documents. On the Review tab, find the Compare button and choose Compare again from the list that opens. In the window that appears, pick the older version under Original document and the newer one under Revised document, then press OK.

Word shows the result in a new document with revision marks: deleted passages are struck through, additions are underlined and coloured. Your two original files are left untouched. Formatting changes such as bold or a different font can be marked too; if you only care about wording, switch formatting off in the expanded settings of the comparison window.

If the documents live in Google Docs, the same job is done with the compare documents command in the Tools menu; the result again opens as a new document with the changes shown as suggestions. You need edit access to both documents for this.

Text in an email or message: copy, paste, compare

If the text sits in an email, a web page or a messaging app, you can compare it without going through Word at all. In the Text Compare tool, paste the old version into the left box and the new one into the right box; the result is listed underneath straight away.

Three marks are all you need to read the output. A line starting with a minus has left the old text; a line starting with a plus has entered the new one. When a line has only been edited, the tool adds a further line beginning with a tilde and marks the changed word with square and curly brackets, so you never have to hunt for the difference between "three months" and "two months" by eye.

The tool treats a line as its unit. That works very well for a contract written clause by clause, because every clause has its own line. Where each paragraph is a single long line, the whole paragraph gets flagged when anything in it changes; in that case look at the tilde line, which is where the actual change is.

Three traps that spoil the result: line breaks, spaces, quotes

A comparison tool looks at characters, not at meaning. Two texts that read the same can come out "changed" from top to bottom for these reasons:

• Line breaks: text pasted out of a PDF or an email has a line break at the end of every line you see on screen, while the same text copied from Word keeps each paragraph on one line. Fix: run both texts through the Clean Up Text tool with broken lines joined, so they share the same layout.
• Spaces: the whitespace setting in Text Compare skips only leading and trailing blanks on each line; a double space between two words still counts as a change. Collapse repeated spaces in both texts beforehand.
• Quotes and dashes: Word turns straight quotes into curly ones and hyphens into dashes as you type. When one text comes from Word and the other from a plain email, these marks differ. The smart quotes option in Clean Up Text straightens both.

When one or both versions are PDFs

Contracts very often arrive as PDFs. If you have two PDFs, the Compare PDF Files tool reads the text of both page by page and writes the differences, with page numbers, into a report file; in word-by-word mode it catches a single changed word. It already ignores the spacing differences that PDF layout tends to produce.

Know its limit: only the text is compared. A scanned PDF — a paper page photographed — has no text to read, and a change on a signature page or a moved logo will not appear in the report. If one version is Word and the other a PDF, extract the PDF's text with the PDF to Text tool, copy the text out of the Word file and put both side by side in Text Compare. In this mixed case the line-break trap above is almost certain to appear, so do not skip the clean-up.

What to look for in the list of changes

A list of differences tells you what changed, not what the change means. In contracts and official letters, check these four kinds first:

• Figures and amounts: rent, deposit, penalties, percentages
• Dates and periods: start date, "one year" turned into "two years", the notice period
• Small words that flip meaning: an added "not" or "no", or "may" becoming "must" — short words that hide easily in a long line, which is why the word-level marks matter
• Parties and obligations: has "the tenant shall pay" become "the landlord shall pay", or the other way round

Accepting changes one by one in a shared essay

In a group essay the aim is often not just to see the differences but to decide which of a classmate's corrections to keep. Here Word's comparison result offers something plain text tools cannot: hover over each revision mark and accept or reject it with the buttons on the Review tab. When you are done, you are left with a clean final version without marks.

To avoid the job altogether next time, ask whoever does the corrections to work with Track Changes switched on. Every edit is then recorded as it is made, and no comparison is needed.

Frequently asked questions

How do I compare two documents in Word?

Open one of them, click Compare on the Review tab and pick Compare again from the list. Set the older version as the original and the newer one as the revised document. Word opens a new document with the differences marked; both original files stay as they were.

Can I compare two texts on my phone?

Yes. Text Compare runs in the browser, so it opens on a phone too; copy the two texts and paste them into the boxes. With long documents the small screen gets cramped, so downloading the result as a .txt file and reading it on a computer is more comfortable.

Is finding differences the same as a plagiarism check?

No. Finding differences compares two specific texts you already have. A plagiarism or similarity check compares one text against a large archive of publications and student work; universities use dedicated services for that. The tools on this site do not do that second job.

What happens if I mix up which version is old and which is new?

The marks are reversed: additions show as deletions and deletions as additions. In Text Compare, simply swap the contents of the two boxes; in Compare PDF Files, the option that reverses the order does the same.

No differences were found, but I am sure the texts differ. Why?

There are three likely reasons. You may have selected the same file twice; the change may be purely in formatting, such as a word made bold; or it may sit in an image or a scanned page inside the PDF. A plain text comparison cannot see the last two.

Last updated: October 12, 2026