Can anyone help me clarify the difference between the receiver and the module?

Do you need both to run the radio?

Thanks.

The receiver is what you place in the car to receive the radio signals.

A Module is a RF device that attaches to the radio transmitter to send the signals to the receiver. Not all radios require a module because many if not most have the module built in.

You only need a module if your radio requires one example: Futaba 3PK/PKS, Airtronics M8/M11, etc.

And yes if your radio needs a module then you need both a module and a matching band receiver, i.e.; 75MHz FM, 27MHz FM, 75 MHz PCM, 75 MHz HRS, 2.4 GHz DSM, etc. These are examples of bands.