eared grebe vs black-necked grebe

eared grebe and black-necked grebe both are nouns.

Word	Noun	Adjective	Verb	Adverb
eared grebe	Yes	No	No	No
black-necked grebe	Yes	No	No	No

As nouns, eared grebe and black-necked grebe are synonyms defined as:

eared grebe and black-necked grebe: small grebe with yellow ear tufts and a black neck; found in Eurasia and southern Africa as well as western United States

Other synonyms of eared grebe include Podiceps nigricollis.

eared grebe (noun)	black-necked grebe (noun)
small grebe with yellow ear tufts and a black neck; found in Eurasia and southern Africa as well as western United States	small grebe with yellow ear tufts and a black neck; found in Eurasia and southern Africa as well as western United States