phone tapper vs eavesdropper

phone tapper and eavesdropper both are nouns.

Word	Noun	Adjective	Verb	Adverb
phone tapper	Yes	No	No	No
eavesdropper	Yes	No	No	No

As nouns, eavesdropper is a hypernym of phone tapper; that is, eavesdropper is a word with a broader meaning than phone tapper:

phone tapper (noun)	eavesdropper (noun)
someone who wiretaps a telephone or telegraph wire	a secret listener to private conversations