skipper vs sea captain

skipper and sea captain both are nouns.

Word	Noun	Adjective	Verb	Adverb
skipper	Yes	No	Yes	No
sea captain	Yes	No	No	No

As nouns, skipper and sea captain are synonyms defined as:

skipper and sea captain: an officer who is licensed to command a merchant ship

Other synonyms of skipper include captain, master.

skipper (noun)	sea captain (noun)
the naval officer in command of a military ship	an officer who is licensed to command a merchant ship
an officer who is licensed to command a merchant ship
a student who fails to attend classes

skipper (verb)	sea captain (verb)
work as the skipper on a vessel