red grouse vs ptarmigan

red grouse and ptarmigan both are nouns.

Word	Noun	Adjective	Verb	Adverb
red grouse	Yes	No	No	No
ptarmigan	Yes	No	No	No

As nouns, ptarmigan is a hypernym of red grouse; that is, ptarmigan is a word with a broader meaning than red grouse:

red grouse: reddish-brown grouse of upland moors of Great Britain
ptarmigan: large Arctic and subarctic grouse with feathered feet and usually white winter plumage

red grouse (noun)	ptarmigan (noun)
reddish-brown grouse of upland moors of Great Britain	large Arctic and subarctic grouse with feathered feet and usually white winter plumage