military reserve vs war machine

military reserve and war machine both are nouns.

Word	Noun	Adjective	Verb	Adverb
military reserve	Yes	No	No	No
war machine	Yes	No	No	No

As nouns, war machine is a hypernym of military reserve; that is, war machine is a word with a broader meaning than military reserve:

military reserve: armed forces that are not on active duty but can be called in an emergency
war machine: the military forces of a nation

Other hypernyms of military reserve include armed forces, armed services, military, military machine.

military reserve (noun)	war machine (noun)
armed forces that are not on active duty but can be called in an emergency	the military forces of a nation