underrating vs underestimate

underrating and underestimate both are nouns.

Word	Noun	Adjective	Verb	Adverb
underrating	Yes	No	No	No
underestimate	Yes	No	Yes	No

As nouns, underrating and underestimate are synonyms defined as:

underrating and underestimate: an estimation that is too low; an estimate that is less than the true or actual value

Other synonyms of underrating include underestimation, underreckoning.

underrating (noun)	underestimate (noun)
an estimation that is too low; an estimate that is less than the true or actual value	an estimation that is too low; an estimate that is less than the true or actual value

underrating (verb)	underestimate (verb)
	make a deliberately low estimate
	make too low an estimate of
	assign too low a value to