Orphan pages
This comparison identifies sitemap URLs not reached in the available crawl. They are investigation candidates, rather than proof that a page has no internal links anywhere on the Site.
Investigate before removing
Check crawl completion and limits, then open the URL. Robots restrictions, JavaScript-dependent links, authentication, depth limits or a failed response can prevent observation. A limited run may never have reached the page linking to it.
If the page exists and should be discoverable, review internal navigation with the maintainer. If it was intentionally retired, confirm the desired redirect or removal before updating the sitemap. Do not delete a working sitemap entry solely because one crawl missed it.
Compare later observations after the correction. A page appearing in the next crawl shows that it was reached in that run; it does not establish complete Site coverage. See Pages evidence.