enrollee vs pupil

enrollee and pupil both are nouns.

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

As nouns, pupil is a hyponym of enrollee; that is, pupil is a word with a more specific, narrower meaning than enrollee:

enrollee: a person who enrolls in (or is enrolled in) a class or course of study
pupil: a learner who is enrolled in an educational institution

Other hyponyms of enrollee include educatee, student.

enrollee (noun)	pupil (noun)
a person who enrolls in (or is enrolled in) a class or course of study	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)