gnu goat vs goat antelope

gnu goat and goat antelope both are nouns.

Word	Noun	Adjective	Verb	Adverb
gnu goat	Yes	No	No	No
goat antelope	Yes	No	No	No

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

gnu goat: large heavily built goat antelope of eastern Himalayan area
goat antelope: bovid related to goats but having antelope-like features: mountain goats, gorals, serows, chamois, gnu goats

gnu goat (noun)	goat antelope (noun)
large heavily built goat antelope of eastern Himalayan area	bovid related to goats but having antelope-like features: mountain goats, gorals, serows, chamois, gnu goats