[@tsukune] I've only ever heard Japan and other countries in the east use the term "light novel", usually alongside manga and anime, and I've never actually read any.  I've read books in English that use simplistic narrative, and while I can't offhand remember them being called novels, I think they were just "books" or "chapter books" (or books without pictures, if you were young enough ^.^;  ).  I know that there are books called novels out there that are not particularly sophisticated.  I think Nancy Drew (the old ones) might qualify, and a bunch of YA fiction.  Harry Potter, those are novels, but the language isn't all that complex.

I thought the difference for a light novel is that the main plot -- the big one -- is stretched over multiple books.  Like a serial, where one book is published in pieces.  I could be wrong, of course, but level of artistry in writing has never changed what it's called (save with poetry at times), and I know there's Japanese light novel series with a great deal of flair, from what I've heard.  So take Harry Potter.  Each book has a complete plot, and there are background plot arcs in addition that span multiple books.  Those are novels, and the set is a series.  With a light novel, I'd expect each of those books to be split into multiple smaller pieces, each holding a portion of the "whole" book, and thus the plot of each full story.  I dunno, now that I think on it that doesn't seem quite right either.