bluejacket vs serviceman

bluejacket and serviceman both are nouns.

Word	Noun	Adjective	Verb	Adverb
bluejacket	Yes	No	No	No
serviceman	Yes	No	No	No

As nouns, serviceman is a hypernym of bluejacket; that is, serviceman is a word with a broader meaning than bluejacket:

bluejacket: a serviceman in the navy
serviceman: someone who serves in the armed forces; a member of a military force

Other hypernyms of bluejacket include man, military man, military personnel.

bluejacket (noun)	serviceman (noun)
a serviceman in the navy	someone who serves in the armed forces; a member of a military force