The choice between a servo and stepper motor is an important decision in any system design. In general, the higher the performance requirement (high precision, variable load, high duty cycle, high torque vs. speed) the more likely a servo will be the choice. Where purchase cost is critical, performance is not crucial, and simple set-up is needed, a stepper solution is a cost-effective option.
The following chart compares the performance of brush/brushless servo and stepper motors:
With stepper motors, closing the position loop via an encoder is not an effective means of providing increased precision. Whereas the encoder will provide position verification, the step motor is unable to “servo” to ensure high dynamic performance and repeatability. Adding an encoder and using a microstep driver makes the relative costs of servo and stepper systems roughly equivalent, yet the performance remains decidedly better with servos.