overestimate vs overvaluation

overestimate and overvaluation both are nouns.

Word	Noun	Adjective	Verb	Adverb
overestimate	Yes	No	Yes	No
overvaluation	Yes	No	No	No

As nouns, overestimate and overvaluation are synonyms defined as:

Other synonyms of overestimate include overappraisal, overestimation.

overestimate (noun)	overvaluation (noun)
a calculation that results in an estimate that is too high	too high a value or price assigned to something
an appraisal that is too high	an appraisal that is too high

overestimate (verb)	overvaluation (verb)
make too high an estimate of
assign too high a value to