In my incredibly elementary understanding of superconducting qubits, a qubit is an LC circuit where the inductor has been replaced with a Josephson junction. In this system, microwave pulse operations to implement transformations on the qubit is achieved by a microwave drive line which coupled to the qubit with a capacitor.
In Qiskit Pulse, we usually play our pulses on the DriveChannel, which I assume is directly related to the time varying voltage at the end of the microwave drive line (though I’m a little unsure of where the AWGs come in?). In this big picture, I’m not so sure where the ControlChannel comes into play. All the Qiskit docs say is that it is “associated with multi-qubit gates,” but I am still unsure of how the ControlChannel is physically implemented or when to use it instead of the regular DriveChannel.