sergeant major vs Abudefduf saxatilis

sergeant major and Abudefduf saxatilis both are nouns.

Word	Noun	Adjective	Verb	Adverb
sergeant major	Yes	No	No	No
Abudefduf saxatilis	Yes	No	No	No

As nouns, sergeant major and Abudefduf saxatilis are synonyms defined as:

sergeant major and Abudefduf saxatilis: large blue-grey black-striped damselfish; nearly worldwide

sergeant major (noun)	Abudefduf saxatilis (noun)
large blue-grey black-striped damselfish; nearly worldwide	large blue-grey black-striped damselfish; nearly worldwide
a noncommissioned officer serving as chief administrative officer of a headquarters unit of the Army