General Nomenclature

Authentication/Verification/Keystore

Difference between PIN and Passcode

PIN refers to the one configured at the OS level and entered to unlock the device. i.e. entry and management of the PIN is done by the OS. Face ID and Touch ID (and Android analogues) are the biometric equivalents.

Passcode refers to the numeric string that is managed by the app itself.

User-presence (for access)

Wallet keys can be protected by the OS, so that it's only accessible after the OS has checked for user-presence. This means that the OS has locked the key when it was created and requires biometrics (or OS PIN) to unlock the key to reveal it to the user for back up or to sign a transaction/message.