mountain nyala vs antelope

mountain nyala and antelope both are nouns.

Word	Noun	Adjective	Verb	Adverb
mountain nyala	Yes	No	No	No
antelope	Yes	No	No	No

As nouns, antelope is a hypernym of mountain nyala; that is, antelope is a word with a broader meaning than mountain nyala:

mountain nyala: shaggy antelope of mountains of Ethiopia
antelope: graceful Old World ruminant with long legs and horns directed upward and backward; includes gazelles, springboks, impalas, addax, gerenuks, blackbucks, dik-diks

mountain nyala (noun)	antelope (noun)
shaggy antelope of mountains of Ethiopia	graceful Old World ruminant with long legs and horns directed upward and backward; includes gazelles, springboks, impalas, addax, gerenuks, blackbucks, dik-diks