crucian carp vs Carassius vulgaris

crucian carp and Carassius vulgaris both are nouns.

Word	Noun	Adjective	Verb	Adverb
crucian carp	Yes	No	No	No
Carassius vulgaris	Yes	No	No	No

As nouns, crucian carp and Carassius vulgaris are synonyms defined as:

crucian carp and Carassius vulgaris: European carp closely resembling wild goldfish

Other synonyms of crucian carp include Carassius carassius.

crucian carp (noun)	Carassius vulgaris (noun)
European carp closely resembling wild goldfish	European carp closely resembling wild goldfish