goldfish vs Carassius auratus

goldfish and Carassius auratus both are nouns.

Word	Noun	Adjective	Verb	Adverb
goldfish	Yes	No	No	No
Carassius auratus	Yes	No	No	No

As nouns, goldfish and Carassius auratus are synonyms defined as:

goldfish and Carassius auratus: small golden or orange-red freshwater fishes of Eurasia used as pond or aquarium fishes

goldfish (noun)	Carassius auratus (noun)
small golden or orange-red freshwater fishes of Eurasia used as pond or aquarium fishes	small golden or orange-red freshwater fishes of Eurasia used as pond or aquarium fishes