pupil vs enrollee

pupil and enrollee both are nouns.

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

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

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

pupil (noun)	enrollee (noun)
the contractile aperture in the center of the iris of the eye; resembles a large black dot	a person who enrolls in (or is enrolled in) a class or course of study
a learner who is enrolled in an educational institution
a young person attending school (up through senior high school)