Whether or not it has brakes on all axles, which it must. As well as the addition of an electric over hydraulic actuator with a means to control the breaking of the trailer from inside your vehicle on setups that weigh more than 2800kgs.
From BC ministry of transport..
Q. When are brakes required on a trailer?
Brakes are required if the trailer exceeds 1400 kg, or more than 50% of the licensed vehicle weight of the towing unit. When brakes are required, they must be on all axles and there must be an operational breakaway on the trailer in case the towing unit and trailer separate while being towed. These brakes, when applied, must be adequate to maintain control of the trailer, must not affect the direction of travel of the trailer and, where the weight of the trailer exceeds 2800 kg, must be capable of being applied by the driver of the motor vehicle towing the trailer from his or her normal seated position.