spearhead vs war machine

spearhead and war machine both are nouns.

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

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

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