stone pit vs gravel pit

stone pit and gravel pit both are nouns.

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

As nouns, gravel pit is a hyponym of stone pit; that is, gravel pit is a word with a more specific, narrower meaning than stone pit:

Other hyponyms of stone pit include chalk pit, chalkpit.

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