robin redbreast vs thrush

robin redbreast and thrush both are nouns.

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

As nouns, thrush is a hypernym of robin redbreast; that is, thrush is a word with a broader meaning than robin redbreast:

robin redbreast: small Old World songbird with a reddish breast
thrush: songbirds characteristically having brownish upper plumage with a spotted breast

robin redbreast (noun)	thrush (noun)
small Old World songbird with a reddish breast	songbirds characteristically having brownish upper plumage with a spotted breast
	a woman who sings popular songs
	candidiasis of the oral cavity; seen mostly in infants or debilitated adults