sailor boy vs military man

sailor boy and military man both are nouns.

Word	Noun	Adjective	Verb	Adverb
sailor boy	Yes	No	No	No
military man	Yes	No	No	No

As nouns, military man is a hypernym of sailor boy; that is, military man is a word with a broader meaning than sailor boy:

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

Other hypernyms of sailor boy include man, military personnel, serviceman.

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