petty officer vs noncom

petty officer and noncom both are nouns.

Word	Noun	Adjective	Verb	Adverb
petty officer	Yes	No	No	No
noncom	Yes	No	No	No

As nouns, noncom is a hypernym of petty officer; that is, noncom is a word with a broader meaning than petty officer:

petty officer: a noncommissioned officer in the Navy or Coast Guard with a rank comparable to sergeant in the Army
noncom: a military officer appointed from enlisted personnel

Other hypernyms of petty officer include enlisted officer, noncommissioned officer.

petty officer (noun)	noncom (noun)
a noncommissioned officer in the Navy or Coast Guard with a rank comparable to sergeant in the Army	a military officer appointed from enlisted personnel