serviceman vs military man

serviceman and military man both are nouns.

Word	Noun	Adjective	Verb	Adverb
serviceman	Yes	No	No	No
military man	Yes	No	No	No

As nouns, serviceman and military man are synonyms defined as:

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

Other synonyms of serviceman include man, military personnel.

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