longlegs vs kaki

longlegs and kaki both are nouns.

Word	Noun	Adjective	Verb	Adverb
longlegs	Yes	No	No	No
kaki	Yes	No	No	No

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

longlegs: long-legged three-toed black-and-white wading bird of inland ponds and marshes or brackish lagoons
kaki: blackish stilt of New Zealand sometimes considered a color phase of the white-headed stilt

longlegs (noun)	kaki (noun)
long-legged three-toed black-and-white wading bird of inland ponds and marshes or brackish lagoons	blackish stilt of New Zealand sometimes considered a color phase of the white-headed stilt
	small deciduous Asiatic tree bearing large red or orange edible astringent fruit