Jack-tar vs Jack

Jack-tar and Jack both are nouns.

Word	Noun	Adjective	Verb	Adverb
Jack-tar	Yes	No	No	No
Jack	Yes	No	No	No

As nouns, Jack-tar and Jack are synonyms defined as:

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

Jack-tar (noun)	Jack (noun)
a man who serves as a sailor	a man who serves as a sailor