thrush nightingale vs thrush

thrush nightingale and thrush both are nouns.

Word	Noun	Adjective	Verb	Adverb
thrush nightingale	Yes	No	No	No
thrush	Yes	No	No	No

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

thrush nightingale: large nightingale of eastern Europe
thrush: songbirds characteristically having brownish upper plumage with a spotted breast

thrush nightingale (noun)	thrush (noun)
large nightingale of eastern Europe	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