Allegory is similar to metaphor, but is usually more elaborate. In an allegorical narrative, each character (or, sometimes, object) has both a literal meaning and a consistent metaphorical meaning, and the story proceeds on two levels at once. Thus, when Spenser’s Redcross Knight fights with the dragon named Error, we see the battle of a knight and a dragon at the literal level, and a conflict between the (generalized) Christian and the idea of error at the allegorical level.
Personification is a crude kind of allegory: abstract qualities are turned into people.
Note: This guide is still in the early stages of development.
Three question marks mean I have to write more on the subject. Bear with me.