Identity testing answers the most basic question a buyer has: is this what it says? For peptides it is usually done by mass spectrometry, comparing the measured mass with the expected mass.
Identity testing
Any test that confirms a sample is the compound on the label, usually by mass.
See it running on your own catalog
Purity does the work these terms describe: batches held until their lab report is in, payments matched to orders, and wording checked before it sends.