The electric brakes are drum and shoe type and are activated by a magnet dragging inside the drum inner face when applied. They have to be adjusted frequently to keep in working condition. The electric/hydraulic brakes are disc brakes with an electric activated pump that applies pressure to the calipers when activated. Usually far superior to the drum type. Kits are available for some axles to convert to electric/hydraulic system. There is a momentary delay in the electric/hydraulic brakes that I have as it takes the pump a second to apply pressure. I have read that there is a system available with no delay but have no info on it. bg