Fiction books represent the stories within the Star Wars universe, also called the Expanded Universe. The adaptations of the films, the spin off novels for adults and kids all fit within this category. If it deals with the characters from the Star Wars Saga, you'll find it here.
The Novels feature the titles that are most readily available and recognized. These stories produced in both Hardcover and Paperback initially featured just the core characters of Luke and Leia, Han and Chewie or Lando Calrissian.With the advent of the term Expanded Universe and the publication of Heir to the Empire in 1991 many new characters were able to take the spotlight, while some stories only focus on EU characters.