irony vs figure of speech

irony and figure of speech both are nouns.

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

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

irony: a trope that involves incongruity between what is expected and what occurs
figure of speech: language used in a figurative or nonliteral sense

Other hypernyms of irony include figure, image, trope.

irony (noun)	figure of speech (noun)
incongruity between what might be expected and what actually occurs	language used in a figurative or nonliteral sense
a trope that involves incongruity between what is expected and what occurs
witty language used to convey insults or scorn