The term "workstation" means nothing at all. It's just a generic name that everybody uses it for as long as I can remember. They even use it for low end arranger keyboards. It just makes the product sound cool and impressive I guess.

It's no different than people considering themselves keyboardist, pianist, guitarist or whatever. The name by itself doesn't suggest the depth of a feature or skill level at all. It's just one big category for everybody which is fine.