common scoter vs scoter

common scoter and scoter both are nouns.

Word	Noun	Adjective	Verb	Adverb
common scoter	Yes	No	No	No
scoter	Yes	No	No	No

As nouns, scoter is a hypernym of common scoter; that is, scoter is a word with a broader meaning than common scoter:

common scoter: a variety of scoter
scoter: large black diving duck of northern parts of the Northern Hemisphere

Other hypernyms of common scoter include scooter.

common scoter (noun)	scoter (noun)
a variety of scoter	large black diving duck of northern parts of the Northern Hemisphere