Compare two lists

Compare two lists when each item is a single text value and your question is whether it appears on one side, both sides, or either side. The workbench returns Common items, Only in A, Only in B, and a Unique union. This is a set comparison. A value repeated five times in one list is still one distinct item for membership counts, although the report preserves its original occurrences and their positions for inspection.

Paste one item per line into List A and List B, then confirm those two lists. You can instead import tables and choose one column from each. Table input is helpful when a list is embedded in a wider catalog or registration export. Choose the actual identifier column, not a visually convenient description that may refer to more than one entity. The two selected columns do not need identical names, and their record positions do not have to align.

Exact matching is the starting point. Alpha and alpha are distinct, as are Alpha and a value containing spaces around Alpha. Ignore case and Trim surrounding whitespace are separate visible options. Choose them only if those differences are irrelevant to your task. They affect the value used for membership comparison while retaining the source text in the report. The original values are not translated when you switch the interface language.

Ignore empty items determines whether blank entries participate. Without that option, an empty item can be a member of a list just like another distinct value. With trimming enabled, a whitespace-only item can become empty for the comparison, so the order implied by these settings matters: normalization is evaluated before the empty-item decision. The text 0, false, NULL, or N/A is not automatically an empty item. Clear such markers explicitly in a preparation step if your task requires it.

Common items are present somewhere in both lists. They do not have to appear on the same line. Only in A contains items with no matching value anywhere in B, and Only in B is the reverse. The Unique union contains every distinct matching value from either side. Its order follows the first occurrence in A, followed by values encountered only in B. This makes the output predictable without sorting or changing either source.

The report includes the value used for matching, original values from A, their source positions, original values from B, and their positions. A repeated item can therefore have several listed locations. These locations are useful for returning to the source and deciding whether repetition was intentional. They do not mean repetition changes the set count. If your question concerns how many times each value appears, this tool's first version is not a frequency-difference report.

Suppose List A contains Alpha, alpha, and Beta, while List B contains a space-padded alpha and Gamma. With exact matching, neither spelling of Alpha matches the padded value. The common set is empty, Only in A contains three items, Only in B contains two items, and the union contains five. This result can look surprising when the eye overlooks surrounding spaces, which is why the matching options must remain visible and deliberate.

Enable both Ignore case and Trim surrounding whitespace, then run again. Alpha and alpha in A now correspond to the padded alpha in B. The common set has one item, Only in A contains Beta, Only in B contains Gamma, and the union contains three items. The common report still shows both original A spellings and the original B value with its spaces, along with all three positions. The comparison identifies membership under a rule without rewriting that evidence.

This workflow is useful for comparing product-code lists, event-code exports, authorized contact lists, tag inventories, and filenames. It can help an organizer see which registration identifiers appear in an attendance export. That result only describes the two supplied lists. It does not establish whether a person truly attended, whether a contact is deliverable, or whether a source system has deleted a record. Verify the completeness and purpose of the exports before drawing a broader conclusion.

A list comparison is not a row-by-row comparison of two columns. If the first item in A is Gamma and the third item in B is Gamma, it is common regardless of position. Nor is this the right tool for comparing several fields of product records by a key; use Compare CSV files for that. Keeping membership, positional equality, and record-level changes distinct prevents an apparently correct count from answering the wrong question.

After running, choose a result view and inspect the counts. Grid search is only a way to locate an item within that view. Open the export dialog and explicitly select the report you want, then choose a file, an archive of all reports, or copied table text. CSV and TSV outputs include report columns and source information rather than silently collapsing the result into unexplained values. Choose TSV if you want tab-delimited table text for pasting into a spreadsheet.

Spreadsheet-safe export prefixes formula-like content and reports the number of affected cells. Raw text keeps the original report values but requires acknowledging the risk of interpretation in a spreadsheet program. Generated output is read back to confirm its shape and values before the final download or copy. Because the report contains original text and positions, it can include information you may not want to share broadly. Review the exported scope with that in mind.