deckhand vs seaman

deckhand and seaman both are nouns.

Word	Noun	Adjective	Verb	Adverb
deckhand	Yes	No	No	No
seaman	Yes	No	No	No

As nouns, seaman is a hypernym of deckhand; that is, seaman is a word with a broader meaning than deckhand:

Other hypernyms of deckhand include gob, Jack-tar, Jack, mariner, old salt, sea dog, seafarer, tar.

deckhand (noun)	seaman (noun)
a member of a ship's crew who performs manual labor	a man who serves as a sailor