egret vs heron

egret and heron both are nouns.

Word	Noun	Adjective	Verb	Adverb
egret	Yes	No	No	No
heron	Yes	No	No	No

As nouns, heron is a hypernym of egret; that is, heron is a word with a broader meaning than egret:

egret: any of various usually white herons having long plumes during breeding season
heron: grey or white wading bird with long neck and long legs and (usually) long bill

egret (noun)	heron (noun)
any of various usually white herons having long plumes during breeding season	grey or white wading bird with long neck and long legs and (usually) long bill