robin vs robin redbreast

robin and robin redbreast both are nouns.

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

As nouns, robin and robin redbreast are synonyms defined as:

robin and robin redbreast: small Old World songbird with a reddish breast

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

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