dielectric vs rock wool

dielectric and rock wool both are nouns.

Word	Noun	Adjective	Verb	Adverb
dielectric	Yes	No	No	No
rock wool	Yes	No	No	No

As nouns, rock wool is a hyponym of dielectric; that is, rock wool is a word with a more specific, narrower meaning than dielectric:

dielectric: a material such as glass or porcelain with negligible electrical or thermal conductivity
rock wool: a light fibrous material used as an insulator

Other hyponyms of dielectric include bushing, mineral wool, glass wool, ferroelectric material.

dielectric (noun)	rock wool (noun)
a material such as glass or porcelain with negligible electrical or thermal conductivity	a light fibrous material used as an insulator