overachiever vs pupil

overachiever and pupil both are nouns.

Word	Noun	Adjective	Verb	Adverb
overachiever	Yes	No	No	No
pupil	Yes	No	No	No

As nouns, pupil is a hypernym of overachiever; that is, pupil is a word with a broader meaning than overachiever:

Other hypernyms of overachiever include educatee, student.

overachiever (noun)	pupil (noun)
a student who attains higher standards than the IQ indicated	the contractile aperture in the center of the iris of the eye; resembles a large black dot
	a learner who is enrolled in an educational institution
	a young person attending school (up through senior high school)