A novel is usually defined as a long narrative containing a distinct beginning, middle and end. Novels tend to focus on a group of characters--both protagonists and antagonists--while featuring multiple storylines. The average length of a novel is about 60,000 to 120,000 words.
Like novels, short stories are generally written in a narrative format. They differ from novels, however, by focusing on a single storyline and featuring fewer characters. Most short stories fall between 1,000 to 7,500 words.
Both plays and screenplays are written for actors to perform. In addition to dialogue, plays and screenplays feature scene and character descriptions, as well as stage or camera directions.
Poetry is one of the oldest forms of creative writing. Traditional poetry often follows a certain rhythm and rhyming pattern, whereas more modern poetry tends to flow free without a definable structure. There is no average word count for poetry--both a haiku (which contains 17 syllables) and an epic narrative like Homer's "Odyssey" are considered poetry.
Short stories that range from about 75 to 1,500 words are categorized as flash fiction. The challenge of flash fiction lies in creating a thorough, meaningful story with only a minimal amount of words.