overestimate vs overappraisal

overestimate and overappraisal both are nouns.

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

As nouns, overestimate and overappraisal are synonyms defined as:

Other synonyms of overestimate include overestimation, overvaluation.

overestimate (noun)	overappraisal (noun)
a calculation that results in an estimate that is too high	an appraisal that is too high
an appraisal that is too high

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