What is the difference between authentication and authorization?

Authorization is used by a server when the server needs to know exactly who is accessing resources, and authentication is a process by which a server determines the permissions.

Authorization allows an engineer to control the user access level privileges to the router, and authentication is the process of giving the user-specific permissions.

Authentication is coupled with authorization so that the server knows who the requestor is, and authorization is used by a requestor that knows the server.

Authentication allows an engineer to identify who can connect to a router, and authorization is the function of specifying access rights and privileges to resources.