On his temporary tor.com blog, Edward M. Lerner (more typically at SF and Nonsense) asks a question: how does a technothriller differ from near-future SF, if at all. Somewhere back there, I think, is the income/status issue I've been seeing a resurgence of lately--"why do they have more mainstream acceptance and why do they make so much more money?"--though, to be fair, Lerner never heads in that direction.
Just remember that, with a writer, "and how does that get me a bigger advance?" is the unspoken addendum to any question, kind of like "between the sheets" for Chinese fortune cookies.
My answer: SF is about the transformation of order, technothrillers are about the reestablishment of order. In an SF novel, a change, particularly a technological change, moves out into society as a whole, and transforms it. In a technothriller, changes, even dramatic ones, are confined to the immediate area of the characters and the plot. In an SF novel, if dinosaurs are recreated, their recreation and the technology behind it gets used in war, in labor, in abstruse spiritual transformations. In a technothriller (Crichton's Jurassic Park books), they stay on their island.
The containment has several related favorable features, as far as a mainstream reader is concerned. Reactions, mores, and cultural features are recognizable. And, as a result, the writer isn't tempted to spend time and energy making up stuff (changing the way people pump gas, or giving them weird new bedroom furniture) just to show that we're in The Future. And the writer can't hide behind the chrome, and has to focus on the engine--the plot.