After reading this thread I seem none the wiser, so I'll wade in with a question.
Which manufacturers ... ?
Diving into a 3-yr old thread possibly won't show current best practise!
Really, you have to go with
Garmin, unless you really can't say 'no' to your non-conformist cyclist gene.
95% of other UK GPS-users out there will be using Garmins, so just run with the herd.
Track: is a line drawn through a list of points, generally the points are quite close together (<100m) so the line follows the roads quite well. It's just like having a highlighted map on the handlebars.
Route: is a line drawn through a list of points, generally the points are much further apart (>500m), so it becomes a join-the-dots from turn to turn. In some ways it's more like a routesheet than a map.
Modern Garmins (with maps installed) have the optional ability to take a Route as above, and combine it with the map information, so that the Route follows the best (hopefully!) roads (rather than straight lines turn-to-turn). Like a car satnav (spit!). In this case it's better to use fewer (but not too few) points, getting the balance right is a fine art.
Three methods, and they all work with a bit of understanding of the pros and cons.