Biometric Verification versus Identification
In a biometric system, it is usual to match a sample against a database called a gallery. If an individual gets a background check from the FBI, it is to check the fingerprints against the gallery of 70 million criminals. Unlocking a phone is searching a gallery of a few examples (3-5) of a finger. Although both of these processes involve biometric matching, they are considered to be fundamentally different in terms of difficulty.
When a phone is unlocked, the phone is checking to see that fingerprint matches the owner, a process called verification. This is also called 1:1 matching because it is the matching of a sample against one person in the gallery. With a background check or a crime scene, there is no guarantee that the sample is in the gallery so the goal is to compare the fingerprint against all of the records to see if there is a match, a process called identification. This process is also called 1:N matching because there is a comparison with every person in the gallery. Consequently, identification is harder than verification and increasing in difficulty with the size of the gallery.