American robin vs robin

American robin and robin both are nouns.

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

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

American robin and robin: large American thrush having a rust-red breast and abdomen

Other synonyms of American robin include Turdus migratorius.

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