How to read the result
The top of the result says how many changes there are, then each line of the text follows with two line numbers, the original’s and the changed version’s:
| Mark | Color | Meaning |
|---|---|---|
| − | Red | Line removed, or the old version of an edited line |
| + | Green | Line added, or the new version of an edited line |
| none | No color | Line is the same in both |
When a line was edited rather than replaced, the words that changed are marked in a darker shade, so in “The meeting is on Tuesday Thursday” you see the one word that moved, not the whole line.
How it works
- Lines first: the two texts are compared line by line with Myers’ difference algorithm, the method behind most “diff” tools, including Git. It finds the smallest set of lines to remove and add to turn the original into the changed version.
- Then words: where removed lines sit right before added lines, they’re paired up as edits and compared again word by word, so only the changed words are marked.
- Options: Ignore capitals and Ignore extra spaces make lines that differ only in those ways count as the same.
Limits
Moved paragraphs show as removed in one place and added in another; the tool doesn’t detect moves. Two very different long texts are shown as fully removed and fully added rather than matched line by line, so the page stays fast.