oyster catcher vs oystercatcher

oyster catcher and oystercatcher both are nouns.

Word	Noun	Adjective	Verb	Adverb
oyster catcher	Yes	No	No	No
oystercatcher	Yes	No	No	No

As nouns, oyster catcher and oystercatcher are synonyms defined as:

oyster catcher and oystercatcher: black-and-white shorebird with stout legs and bill; feed on oysters etc.

oyster catcher (noun)	oystercatcher (noun)
black-and-white shorebird with stout legs and bill; feed on oysters etc.	black-and-white shorebird with stout legs and bill; feed on oysters etc.