c177ed05_Stepper_vs_Servo_Motors_Stepper_Vs__Servo_Motors_Stepper__Hybrid_
[Characteristics] Efficiency [Servo Motor (DC Brushed] Servo motors are very efficient. Yielding 80-90% efficiency given light loads. [Stepper (Hybrid)] 
Stepper motors consume a lot of power given their output, much of which is converted to heat. Stepper motors are usually about 70% efficient but this has some to do with the stepper driver.
Stepper vs Servo Motors
Stepper (Hybrid)