spearhead vs leader

spearhead and leader both are nouns.

Word	Noun	Adjective	Verb	Adverb
spearhead	Yes	No	Yes	No
leader	Yes	No	No	No

As nouns, leader is a hypernym of spearhead; that is, leader is a word with a broader meaning than spearhead:

spearhead: someone who leads or initiates an activity (attack or campaign etc.)
leader: a person who rules or guides or inspires others

spearhead (noun)	leader (noun)
the head and sharpened point of a spear	a featured article of merchandise sold at a loss in order to draw customers
the leading military unit in an attack	a person who rules or guides or inspires others
someone who leads or initiates an activity (attack or campaign etc.)

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