mariner vs Jack

mariner and Jack both are nouns.

Word	Noun	Adjective	Verb	Adverb
mariner	Yes	No	No	No
Jack	Yes	No	No	No

As nouns, mariner and Jack are synonyms defined as:

Other synonyms of mariner include gob, Jack-tar, old salt, sea dog, seafarer, seaman, tar.

mariner (noun)	Jack (noun)
a man who serves as a sailor	a man who serves as a sailor