What is the difference between a steering wheel and a wheel-rim?

A steering wheel has its own circuit board, enabling it to provide a range of functionalities like buttons, rotary switches, REV LEDs, a display for telemetry data, and so on. The steering wheel can directly mount onto a Fanatec wheel base.

A wheel rim is a single component lacking any electronic elements, and it needs always to be mounted on one of Fanatec's hubs. It is important to note that a rim alone cannot be used as a functioning steering wheel.