Electric motors are generally used in portable devices, or generally run smooth, can provide enough power devices, such as fan, electric drill, etc., is its electricity, convenient. Weakness is assuming locked-rotor (do not allow the rotor turn but electricity) due to the formation and rotating vortex cannot, will cause the coil burned. The price is relatively cheap.
Hydraulic motor is generally used in low speed and high capacity do not have access to electricity, such as mixers (transport of concrete) torque hydraulic motor can use very small, like a jack, a person can use a small force, supporting thousands of even tens of thousands of tons is no problem, as long as enough so that the proportion of the design, is convenient to drive high load, low speed devices, such as concrete mixing equipment, is often used in mixing equipment. At the same time, such as crawler excavator crawler drive is also using the hydraulic motor.
Hydraulic motor has a benefit is that the use of liquid pressure pump station, because is the pipe, so that we can to many places, such as excavators, output from the upper part of the pump station of hydraulic oil pump can be to drive forward on the following motion mechanism.