chalcedony vs carnelian

chalcedony and carnelian both are nouns.

Word	Noun	Adjective	Verb	Adverb
chalcedony	Yes	No	No	No
carnelian	Yes	No	No	No

As nouns, carnelian is a hyponym of chalcedony; that is, carnelian is a word with a more specific, narrower meaning than chalcedony:

Other hyponyms of chalcedony include agate, bloodstone, heliotrope, cornelian, chrysoprase, onyx, plasma, sard, sardine, sardius.

chalcedony (noun)	carnelian (noun)
a milky or greyish translucent to transparent quartz	a translucent red or orange variety of chalcedony