wading bird vs heron

wading bird and heron both are nouns.

Word	Noun	Adjective	Verb	Adverb
wading bird	Yes	No	No	No
heron	Yes	No	No	No

As nouns, heron is a hyponym of wading bird; that is, heron is a word with a more specific, narrower meaning than wading bird:

wading bird: any of many long-legged birds that wade in water in search of food
heron: grey or white wading bird with long neck and long legs and (usually) long bill

wading bird (noun)	heron (noun)
any of many long-legged birds that wade in water in search of food	grey or white wading bird with long neck and long legs and (usually) long bill