Jenken,
I'll stand by my statements. I agree with you that there are varying degrees in each category, literary vs mainstream vs genre. However, most genre novels are what I said, primarily plot-driven, whereas, mainstream are primarily character driven with a plot line and theme. I will agree too, that many novels "labeled" mainstream are plot-driven, but become classified as mainstream by their large appeal to a wide audience. However, in my opinion, and it may just be my opinion, many of them are still genre, but with a wide appeal.
Strict literary, on the other hand is more concerned with prosaic style, language, descriptions if you will, of some kind of human condition. It too can be character driven, but usually does not have a plot, or much of one at least. That's why they're boring to read, in my opinion.
Read "Lilies of the Field" or "Red Badge of Courage" for examples of what I mean by literary fiction. I may be wrong, but I had a hard time figuring out a plot line in either of them. Oh, I suppose they had some modicum of a story, but neither of them gripped me, but had wonderful descriptions of the conditions at hand. If they had told a gripping story, rather than repetitious descriptions of conditions, I might have liked them.
I don't mean to be disagreeable, and hope you don't take it that way, but I’ve studied this in some detail. Read Sol Stein’s books on writing, or if you can find it, Dean Koontz’s book titled “How to Write Best Selling Fiction.” I think it’s out of print, but he has an entire chapter devoted to this subject.