goldcrest vs Regulus regulus

goldcrest and Regulus regulus both are nouns.

Word	Noun	Adjective	Verb	Adverb
goldcrest	Yes	No	No	No
Regulus regulus	Yes	No	No	No

As nouns, goldcrest and Regulus regulus are synonyms defined as:

goldcrest and Regulus regulus: European kinglet with a black-bordered yellow crown patch

Other synonyms of goldcrest include golden-crested kinglet.

goldcrest (noun)	Regulus regulus (noun)
European kinglet with a black-bordered yellow crown patch	European kinglet with a black-bordered yellow crown patch