c177ed05_Stepper_vs_Servo_Motors_Stepper_Vs__Servo_Motors_Stepper__Hybrid_
[Characteristics] Direct Drive Capability [Servo Motor (DC Brushed] Servo motors usually require more gearing ratios due to their high RPM. It is very rare to see a direct drive servo motor setup. [Stepper (Hybrid)] 
Stepper motors will work fine in direct drive mode. Many people simple use a motor couple and attach the motor shaft directly to the leadscrew or ballscrew.
Stepper vs Servo Motors
Stepper (Hybrid)