oyster catcher vs shore bird

oyster catcher and shore bird both are nouns.

Word	Noun	Adjective	Verb	Adverb
oyster catcher	Yes	No	No	No
shore bird	Yes	No	No	No

As nouns, shore bird is a hypernym of oyster catcher; that is, shore bird is a word with a broader meaning than oyster catcher:

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

Other hypernyms of oyster catcher include limicoline bird, shorebird.

oyster catcher (noun)	shore bird (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