What is on one list and not the other.

What it does

Compare Two Lists reads each side as a set of items and works out the overlap. It reports what appears in both lists, what appears only in the first, and what appears only in the second. Each item is treated as a whole line (or a whole comma-separated value), not as a sequence of characters, so a difference in order does not matter.

The comparison can ignore case and edge spaces, which is usually what you want when one list came from a form and the other from a spreadsheet. It can also be exact, which is what you want when the casing or the spacing is part of the identifier. The two modes are a single switch, not a hidden assumption.

The three columns

Only in A

Items that appear in the first list and nowhere in the second. In a reconciliation, these are the records the other side is missing.

In both

The intersection. These are the matches. The displayed spelling comes from the first list, so you can see which version of the name or code was treated as canonical.

Only in B

Items that appear in the second list and nowhere in the first. These are the additions, the extras, or the records that only exist on the other side.

Every column has its own copy button, and the whole report can be downloaded as a text file. The report includes the three sections and the similarity figure, which makes it easy to paste into a ticket or an email.

Duplicates and similarity

A list can contain the same item twice. The comparison counts unique items, but it does not pretend the repeats are invisible. A strip below the columns names the items that repeat inside A or inside B. That distinction matters: “Ann appears twice in the source list” is a different problem from “Ann is missing from the other list”.

Jaccard similarity is the size of the intersection divided by the size of the union. If A has four unique items and B has four, and two are shared, the union has six items and the similarity is 2/6, or 33%. It is a compact way to see whether two lists are broadly the same or mostly different. It says nothing about whether the items are spelled correctly or whether they refer to the same real-world thing.

Examples

List A: Ann, Ben, Cara, Dan
List B: ann, Cara, Dan, Elle

Only in A: Ben
In both: Ann, Cara, Dan
Only in B: Elle

“ann” matches “Ann” because case is ignored. “Ben” is missing from the replies, and “Elle” is a reply from someone who was not on the original list. That is the whole reconciliation in three lines.

A: SKU-001, SKU-002, SKU-003
B: SKU-002, SKU-004

Only in A: SKU-001, SKU-003
In both: SKU-002
Only in B: SKU-004

With exact case, a lowercase sku-002 would not match. That is deliberate: SKUs are identifiers, and a case difference may be a real data problem rather than a formatting nuisance.

A: red, blue, red, green
B: blue, green, green

Only in A: — 
In both: blue, green
Only in B: —
Repeated in A: red
Repeated in B: green

The unique comparison is clean, while the duplicate strip still tells you that the source lists contain repeats. Use that information before you trust a count.

Limits worth knowing

• It is not a fuzzy matcher. “Jon” and “John” are different items. “Acme Inc.” and “Acme, Inc.” are different unless you normalize the punctuation first. There is no edit-distance threshold or synonym matching.
• Whitespace inside an item is significant. The trim option only removes spaces at the edges. “New York” and “New York” are different items.
• Delimiters are not escaped. A comma-separated list cannot contain a literal comma inside an item. Use one item per line when the values can contain the delimiter.
• Similarity is a ratio, not a verdict. Two lists can be 100% similar and still be wrong if both contain the same mistake.
• Nothing is stored. The lists disappear on refresh. Copy the report or download it before leaving.

Page updated 27 October 2026