Decide what one item means
Before cleaning, make sure every record occupies one line. A record might be an email address, product ID, keyword, filename, or complete name. Do not split data whose spaces are meaningful.
Clean only what should be ignored
- Use Remove Empty Lines for blank rows.
- Use Remove Duplicate Lines when repeated entries should count once.
- Trim leading and trailing whitespace if those spaces are accidental.
- Ignore capitalization only when uppercase and lowercase do not identify different records.
- Use Sort Lines for easier manual scanning, but not when source order matters.
Run and interpret the comparison
Paste the prepared sources into Compare Lists. “Only in A” can indicate removed or missing records. “In both” confirms overlap. “Only in B” can indicate newly added records.
Normalization changes the question
Exact comparison asks whether two lines are identical. Normalized comparison asks whether they should be considered equivalent after selected differences are ignored. For IDs, filenames, or codes, case and spaces may matter; for email or keyword lists, ignoring them may be appropriate.
Keep an audit trail
Retain the original exports. Cleaning is useful for comparison, but the normalized result should not silently replace a source file when duplicates or order carry business meaning.