The biggest difference between fiction and nonfiction is their respective relation to the truth. Fiction fudges or completely fabricates specific truths, often with the intention of revealing larger truths about humanity or the world. Nonfiction, on the other hand, lets the facts speak for themselves. Both are valuable in very different ways.
Definition of Fiction
A work of fiction is less an accurate description of reality than it is a product of the imagination. For something to be a work of fiction, it does not have to be completely fictitious -- it can take inspiration from factual events or human beings, for example. But if it's an invention or fabrication of the writer, even in part, then it is classified as fiction rather than nonfiction. A work of fiction can be a piece of literature, but it can also be a film or another piece of art.
Types of Fiction
Works of fiction come in as many genres as you can, well, imagine -- which is fitting, since works of fiction are always the product of the imagination. "Gone with the Wind" deals with the American Civil War, but it’s a work of historical fiction; "Lord of the Rings" is a work of high fantasy while "Mary Poppins" is a piece of children’s literature. Romance novels, fantasy novels, postmodern literature, mysteries and horror films: all of these, and so many more, are genres within the broad category of fiction.
Definition of Nonfiction
Nonfiction is -- as its prefix would suggest -- the exact opposite of fiction. Where fiction springs forth from the imagination, nonfiction is directly produced from reality. It doesn’t deal with fancy -- it deals with fact and fact alone. Its aim is to describe people, places and events with as much accuracy as possible, whether or not those people, places and event could be made more interesting with a little creative license. In fact, many supporters of nonfiction would argue that creative license can’t make reality more interesting than it already is -- the truth, they argue, is stranger than fiction.
Types of Nonfiction
Just because the standards of what constitutes nonfiction are more narrow than the standards of what constitutes fiction doesn’t mean that nonfiction doesn’t boast as many genres. News articles, film documentaries, magazine features, biographies, autobiographies, history, science, economics, philosophy and political analysis -- all of these are genres and types of nonfiction. Moreover, just because something is factual doesn’t mean it has to be boring: Michael Moore’s documentaries are classified as works of nonfiction, but they’re hugely interesting to some and controversial to others.