A stepper motor for sale is essentially a servo motor that uses a different method of control. Stepper motors utilize multiple toothed electromagnets arranged around a central gear to define position
We can talk about servo motors as an assembly of four things: a DC motor, a gearing set, a control circuit and a position-sensor (usually a potentiometer).
In industry servo motors are known as motors that can be controlled most precisely. Comparing servo with standard Brushless DC motors, servos usually have three wires (power, ground and control). Power to servo motors is constantly applied. Servo controller regulates the current draw to drive the motor.
DC (Direct Current) motors are two wire (power and ground), continuous rotation motors. When these wires are connected to power supplies, a DC motor starts to spin until that power is removed. Most DC motors run at a high RPM (revolutions per minute). DC motors could be used for computer cooling fans, radio controlled cars or other automotive applications.
This is a short overview of pros and cons of DC vs Stepper vs Servo motors. Hopefully it should help you make a more informed choice with your needs for you project.
Fast, continuous rotation. Finally they are used for anything that needs to spin at a high RPM e.g. car wheels, fans, drills etc.
May be very fast, high torque, very 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 etc. Servos require a feedback mechanism and support circuitry to drive positioning.
Quite slow, precise rotation, easy set up and control. Advantage over servo motors in positional control where turn angle is not limiter. Stepper motors are suited for 3D printers and similar devices where position is fundamental.