war machine vs combat

war machine and combat both are nouns.

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

war 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

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