war machine vs spearhead

war machine and spearhead both are nouns.

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

war machine (noun)	spearhead (noun)
the military forces of a nation	the head and sharpened point of a spear
	the leading military unit in an attack
	someone who leads or initiates an activity (attack or campaign etc.)

war machine (verb)	spearhead (verb)
	be the leader of