brown thrush vs thrasher

brown thrush and thrasher both are nouns.

Word	Noun	Adjective	Verb	Adverb
brown thrush	Yes	No	No	No
thrasher	Yes	No	No	No

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

brown thrush: common large songbird of eastern United States having reddish-brown plumage
thrasher: thrush-like American songbird able to mimic other birdsongs

Other hypernyms of brown thrush include mocking thrush.

brown thrush (noun)	thrasher (noun)
common large songbird of eastern United States having reddish-brown plumage	thrush-like American songbird able to mimic other birdsongs
	large pelagic shark of warm seas with a whiplike tail used to round up small fish on which to feed
	a farm machine for separating seeds or grain from the husks and straw