First of all, the stepper motor driver cannot control the forward and reverse of the stepper motor, but generally sends an analog signal, and the control of the stepper motor forward and reverse is mainly the high and low levels of the controller.
Servo drive, also known as "servo controller" and "servo amplifier", is a kind of controller used to control servo motor, its role is similar to the inverter acting on ordinary AC motor, is a part of the servo system, mainly used in high-precision positioning system.
Generally, the servo motor is controlled by position, speed and torque to achieve high-precision transmission system positioning, which is currently a high-end product of transmission technology.