crucian carp vs Carassius carassius

crucian carp and Carassius carassius both are nouns.

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

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

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

Other synonyms of crucian carp include Carassius vulgaris.

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