What is the difference between a hydraulic pump and a hydraulic motor?

Hydraulic pump and hydraulic motor are essential hydraulic components on every excavator, and their structure and working principle are very similar. White outside some industries sometimes confuse these two things.  Some people say that hydraulic pumps and motors are like generators and motors. They have two kinds of jobs.  Is this description correct?  What is the difference between them?

Similarities between hydraulic motor and hydraulic pump:
(1) In principle, the hydraulic motor and hydraulic pump are reversible. If the motor is used to drive, the output is hydraulic energy (pressure and flow), which is the hydraulic pump.  If pressure oil is input and mechanical energy (torque and rotational speed) is output, it becomes a hydraulic motor.
(2) The two are similar in structure.
(3) In terms of working principle, both of them use the change of sealed working volume to suck and drain oil.  For hydraulic pumps, oil is sucked when the working volume increases and high-pressure oil is discharged when the working volume decreases.  For hydraulic motors, high-pressure oil enters when the working volume increases and low-pressure oil is discharged when the working volume decreases.

The difference between hydraulic motor and hydraulic pump:
(1) The hydraulic pump is an energy device, while the hydraulic motor is an actuating element.  The hydraulic pump is a conversion device that converts mechanical energy of a motor into hydraulic energy, outputs flow and pressure, and expects high volumetric efficiency.  Hydraulic motor is a device that converts the pressure energy of liquid into mechanical energy. It outputs torque and rotational speed in the hope of high mechanical efficiency.
(2) The steering of the output shaft of the hydraulic motor must be able to rotate forward and reverse, so its structure is symmetrical;  However, some hydraulic pumps (such as gear pump, vane pump, etc.) have specific regulations for steering, which can only rotate in one direction and cannot change the direction of rotation at will.
(3) In addition to the oil inlet and outlet, the hydraulic motor has a separate oil leakage port;  Hydraulic pumps generally have only inlet and outlet ports (except axial plunger pumps), and the leaked oil in them is communicated with the inlet port.
(4) The volumetric efficiency of the hydraulic motor is lower than that of the hydraulic pump.
(5) Generally, the working speed of hydraulic pump is relatively high, while the output speed of hydraulic motor is relatively low.  In addition, the gear pump has a large oil suction port and a small oil discharge port, while the gear hydraulic motor has the same oil suction and discharge ports.