agreement vs assent

agreement and assent both are nouns.

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

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

agreement (noun)	assent (noun)
compatibility of observations	agreement with a statement or proposal to do something
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

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