swan vs Cygnus olor

swan and Cygnus olor both are nouns.

Word	Noun	Adjective	Verb	Adverb
swan	Yes	No	Yes	No
Cygnus olor	Yes	No	No	No

As nouns, Cygnus olor is a hyponym of swan; that is, Cygnus olor is a word with a more specific, narrower meaning than swan:

swan: stately heavy-bodied aquatic bird with very long neck and usually white plumage as adult
Cygnus olor: soundless Eurasian swan; commonly domesticated

swan (noun)	Cygnus olor (noun)
stately heavy-bodied aquatic bird with very long neck and usually white plumage as adult	soundless Eurasian swan; commonly domesticated

swan (verb)	Cygnus olor (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