redstart vs redtail

redstart and redtail both are nouns.

Word	Noun	Adjective	Verb	Adverb
redstart	Yes	No	No	No
redtail	Yes	No	No	No

As nouns, redstart and redtail are synonyms defined as:

redstart and redtail: European songbird with a reddish breast and tail; related to Old World robins

redstart (noun)	redtail (noun)
European songbird with a reddish breast and tail; related to Old World robins	dark brown American hawk species having a reddish-brown tail
flycatching warbler of eastern North America the male having bright orange on sides and wings and tail	European songbird with a reddish breast and tail; related to Old World robins