There are two types of servo motors, AC servos and DC servos. The primary difference between your two motors is their way to obtain power. AC servo motors depend on an electric wall plug, rather than batteries like DC servo motors. While DC servo motor performance is dependent only on voltage, AC servo motors are reliant on both frequency and voltage. Because of the complexity of the power supply, AC servo motors can handle high surges, which explains why they are frequently found in industrial machinery.