redbreast vs robin

redbreast and robin both are nouns.

Word	Noun	Adjective	Verb	Adverb
redbreast	Yes	No	No	No
robin	Yes	No	No	No

As nouns, redbreast and robin are synonyms defined as:

Other synonyms of redbreast include Erithacus rubecola, Old World robin, robin redbreast.

redbreast (noun)	robin (noun)
small Old World songbird with a reddish breast	large American thrush having a rust-red breast and abdomen
	small Old World songbird with a reddish breast