corsair vs sea robber

corsair and sea robber both are nouns.

Word	Noun	Adjective	Verb	Adverb
corsair	Yes	No	No	No
sea robber	Yes	No	No	No

As nouns, sea robber is a hypernym of corsair; that is, sea robber is a word with a broader meaning than corsair:

corsair: a pirate along the Barbary Coast
sea robber: someone who robs at sea or plunders the land from the sea without having a commission from any sovereign nation

Other hypernyms of corsair include buccaneer, pirate, sea rover.

corsair (noun)	sea robber (noun)
a swift pirate ship (often operating with official sanction)	someone who robs at sea or plunders the land from the sea without having a commission from any sovereign nation
a pirate along the Barbary Coast