32 amp hot tubs need to be on their own supply this will require a cable installing from the spa to the fuse board, because they are on their own supply they are more powerful and can run the heater and the jets at the same time, they also have more pumping power and typically will have 2 x jet pumps and a separate circulation pump.
13 amp (plug n play) hot tubs can be plugged into an existing outdoor socket and there will be no need for additional electrics to be installed(providing you have an existing outdoor socket) They are limited to the amount of power they can use and can either run the heater or the jets at the same time. they typically have 1 x jet pump that doubles up as a circ pump.