copperhead vs elapid snake

copperhead and elapid snake both are nouns.

Word	Noun	Adjective	Verb	Adverb
copperhead	Yes	No	No	No
elapid snake	Yes	No	No	No

As nouns, elapid snake is a hypernym of copperhead; that is, elapid snake is a word with a broader meaning than copperhead:

copperhead: venomous but sluggish reddish-brown snake of Australia
elapid snake: any of numerous venomous fanged snakes of warmer parts of both hemispheres

Other hypernyms of copperhead include elapid.

copperhead (noun)	elapid snake (noun)
common coppery brown pit viper of upland eastern United States	any of numerous venomous fanged snakes of warmer parts of both hemispheres
venomous but sluggish reddish-brown snake of Australia