Regulus calendula vs ruby-crowned wren

Regulus calendula and ruby-crowned wren both are nouns.

Word	Noun	Adjective	Verb	Adverb
Regulus calendula	Yes	No	No	No
ruby-crowned wren	Yes	No	No	No

As nouns, Regulus calendula and ruby-crowned wren are synonyms defined as:

Regulus calendula and ruby-crowned wren: American kinglet with a notable song and in the male a red crown patch

Other synonyms of Regulus calendula include ruby-crowned kinglet.

Regulus calendula (noun)	ruby-crowned wren (noun)
American kinglet with a notable song and in the male a red crown patch	American kinglet with a notable song and in the male a red crown patch