Definitions from RAAF Publication 95, August 1942.
Course: The course of an aircraft in flight is the horizontal angle from the meridian passing through the aircraft to its longitudinal axis. Thus the course always indicates the direction relative to the meridian in which the aircraft is heading. Except when there is no wind or a wind directly ahead or astern the course of the aircraft is not the direction in relation to the ground along which it travels.
Track: The track of an aircraft is the horizontal angle from the meridian passing through the aircraft to a line representing the direction in relation to the ground along which it flies.
As eckhard cites, course means heading.