metonymy vs figure of speech

metonymy and figure of speech both are nouns.

Word	Noun	Adjective	Verb	Adverb
metonymy	Yes	No	No	No
figure of speech	Yes	No	No	No

As nouns, figure of speech is a hypernym of metonymy; that is, figure of speech is a word with a broader meaning than metonymy:

metonymy: substituting the name of an attribute or feature for the name of the thing itself (as in `they counted heads')
figure of speech: language used in a figurative or nonliteral sense

Other hypernyms of metonymy include figure, image, trope.

metonymy (noun)	figure of speech (noun)
substituting the name of an attribute or feature for the name of the thing itself (as in `they counted heads')	language used in a figurative or nonliteral sense