military machine vs combat

military machine and combat both are nouns.

Word	Noun	Adjective	Verb	Adverb
military machine	Yes	No	No	No
combat	Yes	No	Yes	No

military machine (noun)	combat (noun)
the military forces of a nation	an engagement fought between two military forces
	the act of fighting; any contest or struggle

military machine (verb)	combat (verb)
	battle or contend against in or as if in a battle