ABSTRACT
Many people confuse synecdoche and metonymy because they are both figures of speech in which one noun represents another. The difference is that with synecdoche the equated nouns bear a special relationship to each other:
A is part of B (as hand is of human being) A includes B (as union does members) A was used in making B (as stage is made of boards)
With metonymy, one noun (A) is used for another (B) when A is closely associated with B, thus crown for monarch in:
The Gambia was once a crown colony.