A play is a narration expressed as a dialogue, although there may also be a monologue, known as one-man. Just as any other narration has a plot or argument in which it develops in three times or parts: exposure, climax and denouement. A play can have several genres, including drama.
The drama is relative within the theatrical universe, which can mean both the genre and the conflict of the stage action itself, being used to indicate conflicting actions in a play or literature.
Drama is the genre of literature to which plays belong because drama doesn't just occur in plays it also occurs around you and most plays doesn't always have drama in them as well as poems. Hope this helps! :)
