To me, a semantic distinction at best. There are always degrees of involvement and enthusiasm in nearly any activity. The guy who just buys a bike and perhaps rides it around the block with his kids and knows nothing of the history or theory or principals.... And the complete bike nerd who eschews automobiles and dreams only of his next titanium upgrade.... Both are "cyclists"; its just a matter of degree.
I like to learn what I can when I get involved in something...I know much of the history of cycling and I do all my own maintenance.... But I couldn't go into the theory of frame geometry and the advanced technical details of cycling machines... That's yet another level.