Difference between a GPX Route and a GPX Track?

I'm finding this website very helpful as I'm fairly new to this. I can't understand the difference between a GPX route and a GPX track when I download a cycle route that my group leader has devised. I initially tried a GPX ROUTE, as that was smaller and marked the turns, but that often seemed to take me in a straight line across fields, and confuse my Garmin which said I was off course a lot of the time. When I looked at the generated GPX files, I also noticed a 5 metre difference in the elevations between a ROUTE and a TRACK for identical latitude /  longitude co-ordinates. Perhaps someone could explain this? Thanks very much!