What is the difference between Servo motor and Stepper motors?

Stepper Motor is used for RPM below 2000 rpm and Low torque application.wherer as a Servo motor is high precision and high speed application and requires more accelation and decelaration 

Servo Motors

Fast, high torque, accurate rotation within a limited angle – Generally a high performance alternative to stepper motors, but more complicated setup with PWM tuning. Suited for robotic arms/legs or rudder control etc.

Stepper Motors

Slow, precise rotation, easy set up & control – Advantage over servo motors in positional control. Where servos require a feedback mechanism and support circuitry to drive positioning, a stepper motor has positional control via its nature of rotation by fractional increments. Suited for 3D printers and similar devices where position is fundamental.

SERVO MOTOR ARE USED IN HIGHER SPEED APPLICATION THAT MORE ACCELERATION AND DEACCELERATION TYPE...

STEPPER MOTOR ARE USED IN LOWER SPEED APPICATON ... COMPARE TO SERVO 

Thanks for invitation but this question got enough answers with reasonable explanation, hope to be useful

Stepper Motors are generally operated under open-loop control. Commands determine the specified movement of the Stepper Motor. In rare instances, Stepper Motors can stall or lose steps, due to resonance issues or unexpected force. While it is a rare occurrence, the possibility is a drawback for Stepper Motor technology. Stepper Motors can operate in a closed-loop configuration. However, this results in a costly system design. Servo Motors offer constant positional feedback. Constant feedback eliminates the potential for stalling, and allows the motor to correct any positioning discrepancies. The closed-loop configuration that Servo Motors offer allows the motor to generate faster speeds and up to three times the torque than their Stepper counterparts. 

servomotor system used closed loop possible with encoder function but in the stepper motor use as open loop control.we can apply heavy load in servo motor with no affect the performance in the stepper motor we cannot apply more than desired load.

stepper motor spped is slow comparing with servo(high speed)

construction vice very complication for servo than the stepper motor.

servo motor cant control while stepper motor you can control.

Acceleration. Stepper motors are not as flexible with torque as are servo motors. Stepper motors require much more power on acceleration that at any other time therefore torque requirements must lie within the nominal curve for the stepper motor. Peak torque for a servo motor must lie within peak torque curve and the Root Mean Square torque of the overall cycle.

servo motor is Fast, has high torque and accurate rotation within a limited angle 

stepper motor is Slow, has precise rotation and easy set up and control 

comparison: http://www.ni.com/white-paper/3656/en/

stepper: http://www.ni.com/white-paper/14876/en/

servomotor:http://www.ni.com/white-paper/14863/en/

The basic difference between a traditional stepper and a servo-based system is the type of motor and how it is controlled. Steppers typically use 50 to 100 pole brushlessmotors while typical servo motors have only 4 to 12 poles.