assent vs agreement

assent and agreement both are nouns.

Word	Noun	Adjective	Verb	Adverb
assent	Yes	No	Yes	No
agreement	Yes	No	No	No

As nouns, agreement is a hypernym of assent; that is, agreement is a word with a broader meaning than assent:

assent (noun)	agreement (noun)
agreement with a statement or proposal to do something	compatibility of observations
	the thing arranged or agreed to
	the verbal act of agreeing
	the statement (oral or written) of an exchange of promises
	the determination of grammatical inflection on the basis of word relations
	harmony of people's opinions or actions or characters

assent (verb)	agreement (verb)
to agree or express agreement