Posted By Alfred Zoppi
Stepper motors typically cause more vibration due to the fact that they are "stepping" (moving in small increments at a time). Servos can be made to run at a smooth, constant rate so the inherent vibration should be less than a stepper driven system (although you can make a servo'ed motor make lots of vibration and noise if not properly tuned to the load it is moving). Servos require an encoder and some sort of control circuitry to read the encoder information and adjust power to the servo motor as needed to keep the motor running at the desired rate. Stepper motors can use encoders to monitor motion, but the main advantage of a stepper motor is you can run it without encoders and associated control circuitry which makes for a simpler and less expensive system. You just send the stepper motor the no. of stepping pulses and the rate (frequency) of the pulses to "tell" it how much and how fast to move. In summary: Steppers, typically less expensive but rougher motion. Servos, more expensive but smoother motion.