air force vs military service

air force and military service both are nouns.

Word	Noun	Adjective	Verb	Adverb
air force	Yes	No	No	No
military service	Yes	No	No	No

As nouns, military service is a hypernym of air force; that is, military service is a word with a broader meaning than air force:

Other hypernyms of air force include armed service, service.

air force (noun)	military service (noun)
the airborne branch of a country's armed forces	land tenure by service in the lord's army
	a force that is a branch of the armed forces