Brushless servomotors run in closed-loop mode, requiring a feedback device. Stepper motors do not require feedback.
If an unexpected load is encountered, a brushless motor will correct its position. A stepper motor will not recognize when its torque limit has been exceeded.
Brushless servomotors can run at much higher speeds (3000 to 6000 rpm) than steppers (1500 to 3000 rpm), and are not subject to the overheating phenomenon seen in steppers.
Stepper systems are easier to maintain because there are no feedback devices.
When comparing systems of the same torque capacity, a stepper system costs less than a brushless servo system.
Brushless servomotors are more sensitive than stepper motors to fluctuations in load mass.
The largest stepper motors can deliver around 2000 W of shaft power. Brushless servomotors are capable of providing much higher power.
Brushless servomotors usually have resolutions between 500 and 4000 counts/rev. Stepper motors are manufactured with nominal resolutions of 200 steps/rev. However, some stepper drives can achieve resolutions of 50000 pulses/rev.
Stepper motors are well-suited to digital control from computers and other digital devices. Most brushless servomotors use an analog controller and resolver or encoder feedback, requiring a more sophisticated and costly controller.
Nearly all stepper motors conform to the NEMA flange dimensions so they can be easily be replaced, even between different brands.
Stepper motors are inherently noisy, while brushless servomotors don’t exhibit this problem.
Stepper motors apply full rated motor current through the motor windings, no matter the applied load. A servomotor only consumes current as needed to achieve desired rotor positioning.