corsair vs sea rover

corsair and sea rover both are nouns.

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

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

corsair: a pirate along the Barbary Coast
sea rover: 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 robber.

corsair (noun)	sea rover (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