Decide what “duplicate” means
Remove Duplicate Lines keeps the first matching line. By default, matching is exact. Turn on Ignore case if Apple and apple should count as the same item. Trim before comparing treats surrounding spaces as insignificant for the match, but keeps the original text of the first retained line. UseRemove empty lines only when blank rows have no meaning in your list.
For this input, enabling Ignore case produces Apple followed by Pear:
Apple
apple
Pear
AppleThe second and fourth lines match the first after case is ignored. Their removal does not sort the list or rewrite the surviving Apple line.
Compare versions after cleanup
Use Text Diff when the question is “what changed between these two versions?” rather than “which lines repeat inside one list?” Paste the original and revised text into its separate inputs. For example, comparing alpha / beta / gamma withalpha / gamma / delta as three lines each shows beta removed anddelta added; alpha and gamma remain unchanged.
Text Diff can ignore case and whitespace for comparison while still displaying the original lines. It compares lines, so it is not a character-level proof that two documents are identical. Large inputs can hit the tool's browser-side comparison limit.
Check the result you actually need
- Keep a copy of the original when line order or blank rows matter.
- Choose comparison options before copying the deduplicated output.
- Use the diff on the two versions you intend to compare.
- If you need a size check after editing, use Word & Character Counter on the final text.