Autopilot and Flight Director

Very big difference - the AutoPilot takes over the control of the aircraft, in terms of controlling the Ailerons to steer the plane, the Elevator to pitch the plane or keep it level, the Rudder to prevent Yaw, and on planes with an AutoThrottle, the Airspeed.

The Flight Director does not in anyway control the Airplane.... it provides guidance to help the Pilot fly the plane in the same way as the info you have selected in the MCD (AutoPilot) displays....

So if you select Heading 160 in the AutoPilot's Heading display, the Flight Director will indicate a cross-hair (or "Bird) on the display that shows the Pilot which direction to fly the plane in order to maintain Heading 160.

In simple terms; Think of the AutoPilot as an automated pilot system and think of the Flight Director as a guidance system.