external ear vs external organ

external ear and external organ both are nouns.

Word	Noun	Adjective	Verb	Adverb
external ear	Yes	No	No	No
external organ	Yes	No	No	No

As nouns, external organ is a hypernym of external ear; that is, external organ is a word with a broader meaning than external ear:

external ear: the part of the ear visible externally
external organ: an organ that is situated on or near the surface of the body

external ear (noun)	external organ (noun)
the part of the ear visible externally	an organ that is situated on or near the surface of the body