black-winged stilt vs long-legs

black-winged stilt and long-legs both are nouns.

Word	Noun	Adjective	Verb	Adverb
black-winged stilt	Yes	No	No	No
long-legs	Yes	No	No	No

As nouns, long-legs is a hypernym of black-winged stilt; that is, long-legs is a word with a broader meaning than black-winged stilt:

black-winged stilt: stilt of Europe and Africa and Asia having mostly white plumage but with black wings
long-legs: long-legged three-toed black-and-white wading bird of inland ponds and marshes or brackish lagoons

Other hypernyms of black-winged stilt include Himantopus stilt, longlegs, stilt, stilt plover, stiltbird.

black-winged stilt (noun)	long-legs (noun)
stilt of Europe and Africa and Asia having mostly white plumage but with black wings	long-legged three-toed black-and-white wading bird of inland ponds and marshes or brackish lagoons