earless seal vs hair seal

earless seal and hair seal both are nouns.

Word	Noun	Adjective	Verb	Adverb
earless seal	Yes	No	No	No
hair seal	Yes	No	No	No

As nouns, earless seal and hair seal are synonyms defined as:

earless seal and hair seal: any of several seals lacking external ear flaps and having a stiff hairlike coat with hind limbs reduced to swimming flippers

Other synonyms of earless seal include true seal.

earless seal (noun)	hair seal (noun)
any of several seals lacking external ear flaps and having a stiff hairlike coat with hind limbs reduced to swimming flippers	any of several seals lacking external ear flaps and having a stiff hairlike coat with hind limbs reduced to swimming flippers