gravel pit vs stone pit

gravel pit and stone pit both are nouns.

Word	Noun	Adjective	Verb	Adverb
gravel pit	Yes	No	No	No
stone pit	Yes	No	No	No

As nouns, stone pit is a hypernym of gravel pit; that is, stone pit is a word with a broader meaning than gravel pit:

Other hypernyms of gravel pit include pit, quarry.

gravel pit (noun)	stone pit (noun)
a quarry for gravel	a surface excavation for extracting stone or slate