I can still remember when "bike" stood for anything and everything with two wheels that was powered by a human. At some point, we started calling one particular bike a "banana bike". Then we differentiated between "bikes" and "ten speeds". Ten speeds turned into "road bikes", and anything that went in the dirt without getting a flat was called a "mountain bike". Those conventions lasted many years. As I recall, "down hill" came next, and that settled for another few years. Then the skies opened up, and we have as many terms for different types of bikes as we have people to ride them. And what was once a down hill became an enduro, then a trail, then an all mountain, and will probably soon be referred to as an XC. Kinda like the Eagles' rock music of the 70's would be considered country today...
My opinion, terms are used more for marketing, and less for what a bike really does. What a bike does, or is capable of, is more up to the rider and what they want to do with it than the term associated with it.