sparrow vs tree sparrow

sparrow and tree sparrow both are nouns.

Word	Noun	Adjective	Verb	Adverb
sparrow	Yes	No	No	No
tree sparrow	Yes	No	No	No

As nouns, tree sparrow is a hyponym of sparrow; that is, tree sparrow is a word with a more specific, narrower meaning than sparrow:

sparrow: any of several small dull-colored singing birds feeding on seeds or insects
tree sparrow: Eurasian sparrow smaller than the house sparrow

Other hyponyms of sparrow include English sparrow, house sparrow, Passer domesticus, Passer montanus.

sparrow (noun)	tree sparrow (noun)
any of several small dull-colored singing birds feeding on seeds or insects	Eurasian sparrow smaller than the house sparrow
small brownish European songbird	finch common in winter in the northern U.S.