antagonist vs foe

antagonist and foe both are nouns.

Word	Noun	Adjective	Verb	Adverb
antagonist	Yes	No	No	No
foe	Yes	No	No	No

As nouns, foe is a hyponym of antagonist; that is, foe is a word with a more specific, narrower meaning than antagonist:

Other hyponyms of antagonist include dueler, duelist, dueller, duellist, enemy, foeman, opposition, Luddite, withstander.

antagonist (noun)	foe (noun)
a drug that neutralizes or counteracts the effects of another drug	a personal enemy
a muscle that relaxes while another contracts	an armed adversary (especially a member of an opposing military force)
someone who offers opposition