guesstimate vs estimate

guesstimate and estimate both are nouns.

Word	Noun	Adjective	Verb	Adverb
guesstimate	Yes	No	Yes	No
estimate	Yes	No	Yes	No

As nouns, estimate is a hypernym of guesstimate; that is, estimate is a word with a broader meaning than guesstimate:

Other hypernyms of guesstimate include approximation, estimation, idea.

As verbs, estimate is a hypernym of guesstimate; that is, estimate is a word with a broader meaning than guesstimate:

Other hypernyms of guesstimate include approximate, gauge, guess, judge.

guesstimate (noun)	estimate (noun)
an estimate that combines reasoning with guessing	a judgment of the qualities of something or somebody
	an approximate calculation of quantity or degree or worth
	the respect with which a person is held
	a document appraising the value of something (as for insurance or taxation)
	a statement indicating the likely cost of some job

guesstimate (verb)	estimate (verb)
estimate based on a calculation	judge tentatively or form an estimate of (quantities or time)
	judge to be probable