night heron vs heron

night heron and heron both are nouns.

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

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

night heron: nocturnal or crepuscular herons
heron: grey or white wading bird with long neck and long legs and (usually) long bill

night heron (noun)	heron (noun)
nocturnal or crepuscular herons	grey or white wading bird with long neck and long legs and (usually) long bill