Simple / basic answer:
A route is generally, a pre-planned or device generated journey, either A to B, or from A to B, via defined intermediate points. As a rule, routes will also contain data which will allow a GPS device to give visual or audible instructions. For example, “At the roundabout, take the second exit”.
Tracks fall into two categories.
1. A recording, made by the GPS of the roads ridden. Think of it like an electronic trail of breadcrumbs.
2. A line on a GPS device‘s map screen, rather like a highlighter pen, run over a paper map. These are navigable, in the sense that the device will show both the vehicle’s position on the map screen, along with the line of the track and (on some devices) scroll the map as the journey progresses. Unlike routes, tracks generally contain no visual or audible instructions.
Routes are most often used where there are obvious roads to drive along. Tracks, most often when there are no roads (for instance, a desert) or on the so called ‘trails’ which do not feature on most day-to-day electronic maps.