I imagine the noun "course" implies a smooth and well-maintained road but the noun "track" implies a rough road and not really maintained. But some dictionary says "on course" and "on track" both are used as "likely to achieve something". Is there any difference between "on course" and "on track" in the condition of the path they take.
As nouns the difference between course and track is that course is a path, sequence, development, or evolution while track is a mark left by something that has passed along; as, the track, or wake, of a ship; the track of a meteor; the track of a sled or a wheel.
As verbs the difference between course and track is that course is to run or flow (especially of liquids and more particularly blood) while track is to observe the (measured) state of an object over time.
So on course is more like a being on the designated path while being on track is to work to achieve or reach what is required, irregardless of path followed.
On course is the terminology used for ships and planes that are moving towards a destination point. The paths to that destination point are infinite. Ships and planes travel in open areas which allows captains or pilots to navigate and choose their paths. The line of travel for a train is already laid out on railroad. A train needs to follow a certain path to it's destination. On course implies options and the ability to determine a route versus on track being a clearly defined, proven way.