A storey (British English) or story (American English) is any level part of a building with a floor that could be used by people (for living, work, storage, recreation, etc.). Plurals for the word are storeys (UK) and stories (US).
Storey refers to a floor in a building. Story refers to a fictional narrative or tale about a series of events.
In American English, story can mean both a tale and a level of a building.
