Setting aside the obvious difference of number of pages, a novel is a full-length portrait of a protagonist and a flushed out portrait of several supporting characters, with a detailed description of the environment, the time of year, the complexities of the protagonist’s situation that puts him/her in a conflict of some sort (or several sorts); a short story is usually a “sketch” of the main character, in a specific environment, solving a specific dilemma. The key word is “complexity”: A short story is specific, a close-up of the story, but a novel is a broad landscape peopled with a varied number of human specimens. Think of a few days of your diary vs. the whole year’s diary. Interestingly, literary history is riddled with examples of blurred lines between the genres – Moby Dick is definitely a novel, but what about “Bartelby the Scrivener”? For Whom the Bell Tolls is definitely a novel, but what about “The Old Man and the Sea”? In the final analysis, it is a distinction that need only be made when citing and/or editing the terms: so-called novel titles are underlined or put in italics, while short-story titles are put in quotation marks.