"This raises an important question—what’s the difference between an actuator and a motor? The
answer is subtle and relates to the device’s function, not its structure. A motor is a device that con-
verts energy into motion. An actuator is a specific type of motor whose motion is intended to control
another mechanism.
For example, one common application of a linear actuator is to control the position of a mechanical
switch. In this case, the actuator is called a relay. Other actuators open and close valves. In contrast,
if a device’s purpose is simply to effect motion, such as spinning the wheels of a remote-controlled
car or rotating the propellers of a quadcopter, it’s a motor, not an actuator.
Another difference between linear actuators and linear motors involves the nature of the input
power. Every linear actuator I’ve encountered requires DC power, but as later sections will show,
linear synchronous motors and linear induction motors rely on AC power."
Source: Motors for Makers A Guide to Steppers, Servos, and Other Electrical Machines