I guess the problem is defining how far you are willing to stretch for your subspecies. They're not true dragons. It's a taxonomic thing. They have the dragon subtype like drakes do but different Fantasy worlds will determine that to be correct or incorrect. Like how an electric eel is not actually an eel. Or how daddy long-legs aren't actually spiders, alligators aren't lizards.
Taking fantasy worlds like D&D for example. Faerie dragons are biologically similar to dragons, but otherwise lack a lot of the universal traits shared among chromatic and metallic dragons. They would more be defined under fairy folk, and from what I can tell this way of thinking is more agreed on. However im sure you can find some fantasy worlds where this might not be the case and the subtype tag line isn't actually a tag line but a relative that just has strange biological difference.