A Pro Cab and a Power Cab look almost identical but they are two completely different products!
A Pro Cab is only a Cab / Throttle. It requires a DCC system to function. It is a dumb terminal with a keypad and a display. This means you will also need a command station and a booster.
The Power Cab is a self-contained DCC system in one package. It is a Cab / Throttle, it is a DCC Command Station, and it is a Booster. All three in one package.