This document summarizes the key differences between metaphor and metonymy. Metaphor involves mapping between two different conceptual domains, using one domain to help understand another. Metonymy instead relies on connections within a single domain, such as part-to-whole or producer-product relationships. While metaphor comparisons are based on similarity, metonymic substitutions rely on contiguity or connection between concepts. The document also provides examples of metaphors and metonymies, and explains how metonymy can serve particular stylistic functions through meronomic agency or caricature techniques.