ear vs pinna

ear and pinna both are nouns.

Word	Noun	Adjective	Verb	Adverb
ear	Yes	No	No	No
pinna	Yes	No	No	No

As nouns, ear and pinna are synonyms defined as:

ear and pinna: the externally visible cartilaginous structure of the external ear

Other synonyms of ear include auricle.

ear (noun)	pinna (noun)
the sense organ for hearing and equilibrium	the externally visible cartilaginous structure of the external ear
the externally visible cartilaginous structure of the external ear	division of a usually pinnately divided leaf
good hearing
attention to what is said
fruiting spike of a cereal plant especially corn