avowal vs assertion

avowal and assertion both are nouns.

Word	Noun	Adjective	Verb	Adverb
avowal	Yes	No	No	No
assertion	Yes	No	No	No

As nouns, assertion is a hypernym of avowal; that is, assertion is a word with a broader meaning than avowal:

avowal: a statement asserting the existence or the truth of something
assertion: a declaration that is made emphatically (as if no supporting evidence were necessary)

Other hypernyms of avowal include asseveration, averment.

avowal (noun)	assertion (noun)
a statement asserting the existence or the truth of something	a declaration that is made emphatically (as if no supporting evidence were necessary)
	the act of affirming or asserting or stating something