Access Control is any mechanism by which a system grants or revokes the right to access some data, or perform some action. Normally, a user must first Login to a system, using some Authentication system. Next, the Access Control mechanism controls what operations the user may or may not make by comparing the User ID to an Access Control database.
Biometrics is the measurement and statistical analysis of peoples physical and behavioral characteristics. The technology is mainly used for identification and access control, or for identifying individuals that are under surveillance. The basic premise of biometric authentication is that everyone is unique and an individual can be identified by his or her intrinsic physical or behavioral traits.