overestimation vs overvaluation

overestimation and overvaluation both are nouns.

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

As nouns, overestimation and overvaluation are synonyms defined as:

Other synonyms of overestimation include overappraisal, overestimate.

overestimation (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