antithesis vs opposition

antithesis and opposition both are nouns.

Word	Noun	Adjective	Verb	Adverb
antithesis	Yes	No	No	No
opposition	Yes	No	No	No

As nouns, opposition is a hypernym of antithesis; that is, opposition is a word with a broader meaning than antithesis:

Other hypernyms of antithesis include oppositeness.

antithesis (noun)	opposition (noun)
the juxtaposition of contrasting words or ideas to give a feeling of balance	the act of hostile groups opposing each other
exact opposite	the action of opposing something that you disapprove or disagree with
	a body of people united in opposing something
	an armed adversary (especially a member of an opposing military force)
	a contestant that you are matched against
	a direction opposite to another
	the relation between opposed entities