grey sea eagle vs sea eagle

grey sea eagle and sea eagle both are nouns.

Word	Noun	Adjective	Verb	Adverb
grey sea eagle	Yes	No	No	No
sea eagle	Yes	No	No	No

As nouns, sea eagle is a hypernym of grey sea eagle; that is, sea eagle is a word with a broader meaning than grey sea eagle:

grey sea eagle: bulky greyish-brown eagle with a short wedge-shaped white tail; of Europe and Greenland
sea eagle: any of various large eagles that usually feed on fish

grey sea eagle (noun)	sea eagle (noun)
bulky greyish-brown eagle with a short wedge-shaped white tail; of Europe and Greenland	any of various large eagles that usually feed on fish
	large harmless hawk found worldwide that feeds on fish and builds a bulky nest often occupied for years