Both trackpoints and waypoints, and even routepoints, can all be used in the same way, i.e. to mark out a route. The software/website you use will then interpret this data to show the route as a line on a map.
As has already been identified, some garmins have a waypoint limit, this is why mapping software is better if it produces a route out of trackpoints.
Our site won’t currently do a waypoint to trackpoint conversion unfortunately. Its not something that I’ve bothered with as most mapping software such as memory map and bikely produce tracks rather then a collection of waypoints.
This is another reason why I have added a route creation tool to our website. I find it frustrating that you have to go to countless different sites, converting files and messing around just to get a route on your GPS!