Lorrie Moore on Short Stories vs. Novels

'Well, it is possible to believe that the busier and more disorganized a writer’s life, the easier it is to write a novel as opposed to a short story. To write a short story, you have to be able to stay up all night. To read it all in one sitting and at some point see the whole thing through in a rush is part of the process. There’s urgency and wholeness in stories. Not necessarily in novels, which may proceed at a more leisurely or erratic pace. A novelist—like the reader of novels—can check in and out of the novel at short intervals. One can write it in pieces, just as it can be read in pieces. A novel’s often a big, sprawling, shapeless thing—even when it’s short. A story is different. One gives birth to a short story—to haul out those tired procreative metaphors. But with a novel, you raise the child—to continue ridiculously in the same metaphorical realm. Like many novelists, I can now work by putting in a couple hours every morning; but short stories require those twelve-hour stretches.' 

'Of course writing is hard work—or a very privileged kind of hard work. A novel is a daily labor over a period of years. A novel is a job. (Story writers working on a novel are typically in pain through the entire thing.) But a story can be like a mad, lovely visitor, with whom you spend a rather exciting weekend.'

http://www.theparisreview.org/interviews/510/the-art-of-fiction-no-167-lorrie-moore