student vs auditor

student and auditor both are nouns.

Word	Noun	Adjective	Verb	Adverb
student	Yes	No	No	No
auditor	Yes	No	No	No

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

student (noun)	auditor (noun)
a learner who is enrolled in an educational institution	a qualified accountant who inspects the accounting records and practices of a business or other organization
someone (especially a child) who learns (as from a teacher) or takes up knowledge or beliefs	someone who listens attentively
	a student who attends a course but does not take it for credit