hunting ground vs opportunity

hunting ground and opportunity both are nouns.

Word	Noun	Adjective	Verb	Adverb
hunting ground	Yes	No	No	No
opportunity	Yes	No	No	No

As nouns, opportunity is a hypernym of hunting ground; that is, opportunity is a word with a broader meaning than hunting ground:

Other hypernyms of hunting ground include chance.

hunting ground (noun)	opportunity (noun)
an area in which game is hunted	a possibility due to a favorable combination of circumstances
a place where opportunities abound