The two disagree, and almost always in the same direction. A test runs on a fast machine on a good connection, which is better than most real conditions, so lab numbers tend to flatter a site. Passing every lab check and still failing in the field is the ordinary outcome rather than a surprise.
Use each for what it is good at. Lab data diagnoses: it tells you which element is slow and what is blocking it. Field data judges: it is the number that counts. If your field report is empty, the site does not have enough traffic for Chrome to report on it yet, which means no assessment exists rather than that you failed one.
Updated August 2026
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