Gramatically this is a simile not a metaphor, but psychologically they are equivalent.
Metaphors are often rich in symbols, complex and full of meaning.
At least that bit's fairly simple. Metaphors are full and rich carriers of information about the unconscious experiences of the individual. They use symbols and relationships between symbols and the meanings of symbols, symbols which are unique to that individual. To help the individual understand and explore their metaphor would take a set of questions which would not corrupt the content of the metaphor with the questionner's own symbols.