Selachii vs subclass Elasmobranchii

Selachii and subclass Elasmobranchii both are nouns.

Word	Noun	Adjective	Verb	Adverb
Selachii	Yes	No	No	No
subclass Elasmobranchii	Yes	No	No	No

As nouns, Selachii and subclass Elasmobranchii are synonyms defined as:

Other synonyms of Selachii include Elasmobranchii, subclass Selachii.

Selachii (noun)	subclass Elasmobranchii (noun)
sharks, rays, dogfishes, skates	sharks, rays, dogfishes, skates