Autopilot: An autopilot is a system used to control the path of an aircraft, marine craft, or spacecraft without requiring constant manual control by a human operator. Autopilots do not replace human operators. Instead, the autopilot assists the operator's control of the vehicle, allowing the operator to focus on broader aspects of operations
Auto Flight: Those units and components furnish a means of automatically controlling the flight of the aircraft. Includes those units and components which control direction, heading, attitude, altitude, and speed.
That portion of the system that uses radio/radar signals, directional and vertical references, air data (pitot-static), computed flight path data, or manually induced inputs to the system to automatically control the flight path of the aircraft through the adjustment to the pitch/roll/yaw axis or wing lift characteristics and provide visual cues for flight path guidance, i.e.: Integrated Flight Director. This includes power source devices, interlocking devices and amplifying computing, integrating, controlling, actuating, indicating, and warning devices such as computers, servos, control panels, indicators, warning lights, etc.