A320 Flight Plan
 

Why is it that on the flight plan page the track and course between waypoints sometimes differ?
Or maybe bearing

You'd have to check that particular flight plan's decode for a correct answer.

Most probably one figure refers to Initial Magnetic Track (i.e. initial magnetic bearing to fly a great circle route between the two waypoints - same as on the FMGC) while the other is a true constant track, probably referred to the True North.