Okay, and after that pompous lead off, let me say that I'm not going to be talking about novels at all. I'm going to be talking about romances.
Not romances in the Fabio-on-the-cover paperbacks, not the Romance section at Borders, not Harlequin (though there'll be things useful in that genre). Not category romance, or genre romance.
I'm talking about romance in literary theory.
A novel is: A book length work of realistic prose fiction.
A romance is: A book length prose narrative treating imaginary characters involved in events remote in time or place and usually heroic, adventurous, or mysterious.
The thing that the two have in common are that they're book length (call it 50,000 words and up), prose (that is, not poetry or drama), and fiction (some people have said that fiction is when the author tells his own lies; non-fiction is when he tells someone else's lies).
The realism issue, then, is the core of the difference between a novel and a romance. The "realistic" books are the mainest of mainstream; they are the literary works.
The vast majority of the things you find in bookstores labeled "novels" are actually romances. That means:
1) imaginary characters
2) events remote in time or place
3) usually heroic, adventurous, or mysterious
More on all of this later.
I'll try to drop by to talk more after I finish my work every day (except when I'm out of town).