auditor vs eavesdropper

auditor and eavesdropper both are nouns.

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

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

auditor (noun)	eavesdropper (noun)
a qualified accountant who inspects the accounting records and practices of a business or other organization	a secret listener to private conversations
someone who listens attentively
a student who attends a course but does not take it for credit