Choose line diff or character diff by the error

Use a text diff to review paragraphs, files, and blocks where added or removed lines matter. Use a character diff for short strings, punctuation, IDs, or an invisible-space bug inside one line.

Before interpreting a noisy result, check line endings, tabs, trailing spaces, and Unicode normalization. A visual match does not always mean the underlying bytes match. Conversely, line wrapping can make a text diff look dramatic when the wording is unchanged.

Compare the smallest meaningful unit first.