underrating vs underestimation

underrating and underestimation both are nouns.

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

As nouns, underrating and underestimation are synonyms defined as:

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

Other synonyms of underrating include underestimate, underreckoning.

underrating (noun)	underestimation (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