trainer vs leader

trainer and leader both are nouns.

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

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

trainer (noun)	leader (noun)
simulator consisting of a machine on the ground that simulates the conditions of flying a plane	a featured article of merchandise sold at a loss in order to draw customers
one who trains other persons or animals	a person who rules or guides or inspires others