What is the difference between RADIUS and TACACS+ for authentication?

Remote Authentication Dial-In User Service, or RADIUS, and Terminal Access Controller Access Control System Plus, or TACACS+, are both protocols for centralized authentication, authorization, and accounting. RADIUS combines authentication and authorization into a single process and encrypts only the password in transit, using UDP ports 1812 and 1813. TACACS+ separates authentication, authorization, and accounting into independent processes and encrypts the entire packet body, using TCP port 49.