These bikes are ones that do not require a License, Number Plate, Helmet or Insurance. They are limited to 15mph and include pedals but have a moped look to them. Some may exceed 15mph but if so, that will only be possible on private land.
Althought categorised as an Electric Assisted Pedal Cycle (EAPC), the default method of propulsion is the electric motor instead with the pedals being used typically when the batteries runout. Traditional EAPCs are ridden with the pedals with the motor assisting when required (Hills etc).