contention vs polemic

contention and polemic both are nouns.

Word	Noun	Adjective	Verb	Adverb
contention	Yes	No	No	No
polemic	Yes	Yes	No	No

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

contention: a contentious speech act; a dispute where there is strong disagreement
polemic: a controversy (especially over a belief or dogma)

Other hyponyms of contention include argle-bargle, argy-bargy, firestorm, sparring, fight.

contention (noun)	polemic (noun)
the act of competing as for profit or a prize	a controversy (especially over a belief or dogma)
a contentious speech act; a dispute where there is strong disagreement	a writer who argues in opposition to others (especially in theology)
a point asserted as part of an argument

contention (adjective)	polemic (adjective)
	of or involving dispute or controversy