tundra swan vs swan

tundra swan and swan both are nouns.

Word	Noun	Adjective	Verb	Adverb
tundra swan	Yes	No	No	No
swan	Yes	No	Yes	No

As nouns, swan is a hypernym of tundra swan; that is, swan is a word with a broader meaning than tundra swan:

tundra swan: swan that nests in tundra regions of the New and Old Worlds
swan: stately heavy-bodied aquatic bird with very long neck and usually white plumage as adult

tundra swan (noun)	swan (noun)
swan that nests in tundra regions of the New and Old Worlds	stately heavy-bodied aquatic bird with very long neck and usually white plumage as adult

tundra swan (verb)	swan (verb)
	to declare or affirm solemnly and formally as true
	move about aimlessly or without any destination, often in search of food or employment
	sweep majestically