lighterman vs seafarer

lighterman and seafarer both are nouns.

Word	Noun	Adjective	Verb	Adverb
lighterman	Yes	No	No	No
seafarer	Yes	No	No	No

As nouns, seafarer is a hypernym of lighterman; that is, seafarer is a word with a broader meaning than lighterman:

Other hypernyms of lighterman include gob, Jack-tar, Jack, mariner, old salt, sea dog, seaman, tar.

lighterman (noun)	seafarer (noun)
someone who operates a barge	a man who serves as a sailor