contention vs asseveration

contention and asseveration both are nouns.

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

As nouns, asseveration is a hypernym of contention; that is, asseveration is a word with a broader meaning than contention:

contention: a point asserted as part of an argument
asseveration: a declaration that is made emphatically (as if no supporting evidence were necessary)

Other hypernyms of contention include assertion, averment.

contention (noun)	asseveration (noun)
the act of competing as for profit or a prize	a declaration that is made emphatically (as if no supporting evidence were necessary)
a contentious speech act; a dispute where there is strong disagreement
a point asserted as part of an argument