Allegory
Allegory is one of four primary ways to express a truth, typically about a fundamental aspect of life. An allegory differs from a parable, a fable, and a metaphor. Sometimes parables and fables are viewed as types of allegories.
An allegory is a description or story that is logical and rings true, while conveying a profound insight about life itself.
The Gospel of John sets forth two very powerful allegories: An allegory the use of a fictional story to explain, criticize, or explore real-world events or persons. In the Bible, Jesus' parables are examples of allegories, and some consider the bride and groom in the Song of Solomon to be an allegory for Jesus and the Church.
The Gospel of John makes use of allegories In modern literature, Animal Farm by George Orwell is a good example of an allegorical novel. It uses animal characters to tell the story of Communism in the Soviet Union, from the revolution to the rise of Stalin.
Compared with a metaphor
An allegory is longer, and more story-like, than a metaphor. Also, an allegory can make sense (although not with the full intended meaning) when interpreted literally, while metaphors do not.