oystercatcher vs shorebird

oystercatcher and shorebird both are nouns.

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

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

oystercatcher: black-and-white shorebird with stout legs and bill; feed on oysters etc.
shorebird: any of numerous wading birds that frequent mostly seashores and estuaries

Other hypernyms of oystercatcher include limicoline bird, shore bird.

oystercatcher (noun)	shorebird (noun)
black-and-white shorebird with stout legs and bill; feed on oysters etc.	any of numerous wading birds that frequent mostly seashores and estuaries