black buck vs antelope

black buck and antelope both are nouns.

Word	Noun	Adjective	Verb	Adverb
black buck	Yes	No	No	No
antelope	Yes	No	No	No

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

black buck: common Indian antelope with a dark back and spiral horns
antelope: graceful Old World ruminant with long legs and horns directed upward and backward; includes gazelles, springboks, impalas, addax, gerenuks, blackbucks, dik-diks

black buck (noun)	antelope (noun)
common Indian antelope with a dark back and spiral horns	graceful Old World ruminant with long legs and horns directed upward and backward; includes gazelles, springboks, impalas, addax, gerenuks, blackbucks, dik-diks