My definition of genre fiction would be crime, romance or horror novels for instance and there is some genre fiction that is of a high standard in terms of the writing, and some that is drivel. So, James Patterson or Agatha Christie are writers in the crime or detective genre, but very different authors in terms of style and in my opinion, quality. I call some genre fiction “pop corn” fiction. Great for reading on a plane or a quick read but often not terribly inspiring in terms of the quality. However, there are of course classics and examples of fine writing in genre fiction too.
In contrast, literary fiction I expect the quality of the writing to be of a higher standard, I expect more developed and sophisticated plots, narrative, characters etc. It may take me longer to read and to get into the book. They may or may not be page turners.
I read both genre and literary fiction but because my time is so precious in terms of fiction reading, I do try to avoid “pop corn” fiction. I want to read books where the writing is of a good standard. It is rare now I will pick up a mainstream novel where the author churns out one after the other following the same old formula.