A metaphor is a figure of speech in which a word or phrase denoting one thing is used in place of another to suggest a likeness or analogy.
Some symbols are, of course, functional metaphors.
Such public symbols are so well recognized within a culture that they not only stand for what they symbolize, they can replace it. Good examples are a lion representing courage and a cross representing Christianity. Basically, both symbols and metaphors stand for something else. An author can use a particular word, object or event as a representation of a more complex or abstract idea which is of special significance to his or her work. While a metaphor has a clear reference to the idea it represents, a symbol does not have such a reference.