Decent distinction, though what I really like about Stephenson is that he does both. His novels are almost always a case of "what if I explore this idea (or concept) and its implications/impacts on society".

I'd split the line more along the old-school of Clarke v. Asimov, where Clarke generally has more believable character development and looks at societal impacts (especially in his later works), and Asimov tends to focus more on technology and ideas, with more two-dimensional characterization.

There's also the straight-out fantasy / rollicking space-cowboy genres.