weaver vs grass finch

weaver and grass finch both are nouns.

Word	Noun	Adjective	Verb	Adverb
weaver	Yes	No	No	No
grass finch	Yes	No	No	No

As nouns, grass finch is a hyponym of weaver; that is, grass finch is a word with a more specific, narrower meaning than weaver:

weaver: finch-like African and Asian colonial birds noted for their elaborately woven nests
grass finch: usually brightly-colored Australian weaverbirds; often kept as cage birds

weaver (noun)	grass finch (noun)
finch-like African and Asian colonial birds noted for their elaborately woven nests	usually brightly-colored Australian weaverbirds; often kept as cage birds
a craftsman who weaves cloth	common North American finch noted for its evening song