Metonymy 

Metonymy:

Definition: Metonymy involves substituting the name of one thing with the name of something else that is closely associated with it, often based on contiguity or a conceptual relationship.

Example:

• The White House issued a statement. (The White House represents the President or the administration.)

• The crown will not be pleased. (The crown refers to the monarch or royal authority.)

How's this different from synecdoche?

synecdoche involves a part-to-whole or whole-to-part relationship, where a part of something is used to represent the whole, or vice versa.

Examples:

All hands on deck. (Hands represent the entire crew or people on the ship.)

The United States won three gold medals in track and field. (The United States represents the athletes from the country.)

Give us this day our daily bread. (Bread stands for all types of nourishment or sustenance.)

Differences:

Nature of Substitution:

In metonymy, the substitution is based on a conceptual or contextual association between the two terms.

In synecdoche, the substitution involves a part-to-whole or whole-to-part relationship.

Association vs. Part-Whole Relationship:

Metonymy relies on a broader association or relationship between the two terms, which may be based on proximity, cause and effect, etc.

Synecdoche specifically involves a relationship where a part represents the whole or vice versa.

Examples: Metonymy often involves using something closely related to the intended meaning, as seen in the examples with "The White House" and "The crown."

Synecdoche involves using a part to represent the whole, like "All hands on deck."

In summary, while both metonymy and synecdoche involve substitution, metonymy relies on broader associations, and synecdoche involves a more specific relationship between parts and wholes.