Old World chat vs thrush

Old World chat and thrush both are nouns.

Word	Noun	Adjective	Verb	Adverb
Old World chat	Yes	No	No	No
thrush	Yes	No	No	No

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

Old World chat: songbirds having a chattering call
thrush: songbirds characteristically having brownish upper plumage with a spotted breast

Old World chat (noun)	thrush (noun)
songbirds having a chattering call	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