longlegs vs shorebird

longlegs and shorebird both are nouns.

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

As nouns, shorebird is a hypernym of longlegs; that is, shorebird is a word with a broader meaning than longlegs:

longlegs: long-legged three-toed black-and-white wading bird of inland ponds and marshes or brackish lagoons
shorebird: any of numerous wading birds that frequent mostly seashores and estuaries

Other hypernyms of longlegs include limicoline bird, shore bird.

longlegs (noun)	shorebird (noun)
long-legged three-toed black-and-white wading bird of inland ponds and marshes or brackish lagoons	any of numerous wading birds that frequent mostly seashores and estuaries