Marine vs shipboard soldier

Marine and shipboard soldier both are nouns.

Word	Noun	Adjective	Verb	Adverb
Marine	Yes	No	No	No
shipboard soldier	Yes	No	No	No

As nouns, Marine and shipboard soldier are synonyms defined as:

Marine and shipboard soldier: a member of the United States Marine Corps

Other synonyms of Marine include devil dog, leatherneck.

Marine (noun)	shipboard soldier (noun)
a member of the United States Marine Corps	a member of the United States Marine Corps