An appreciable difference between short stories and novels revolves around character and setting and plot scope. Short stories limit persons and settings (times, places, and situations) and complications (plot). Novels expand persons and settings and complications. More characters, larger complications, greater setting scope, longer narrative.
From a readers' perspective, an average short story can be read in about half an hour, which is actually the average amount of time for an average reader to read 4,000 words, thus the reason for that publication limit, about as long as a reader might have for a work meal break. A 100,000 word novel takes the same readers about eleven hours. The average novel reading in one sitting time is four hours.
Many of the short stories in progress I read for evaluation purposes tend to justify longer works and vice versa for longer works.
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