Biometric verification confirms one claimed identity by comparing a live sample, such as a fingerprint or a face, with a template stored for that person. One-to-one matching makes a decision about a specific individual, which is what a door reader needs, and it differs from searching a whole database for a match.
The distinction between verifying and identifying is not academic. Verification answers a yes or no question about one person; identification sorts through everyone enrolled.
Verification and identification
A reader that asks for a card and then a fingerprint is verifying, because the card narrows the comparison to one template. A camera scanning a crowd is identifying, comparing each face with a watch list. Identification is slower, less reliable and much harder to justify on privacy grounds.
Template quality and consent
Enrollment decides the result. A hurried fingerprint scan or a face photo taken in poor light produces a template that fails in daily use. Biometric data is also harder to replace than a card, so the enrollment record, the storage location and the consent process deserve a written policy.