superman vs leader

superman and leader both are nouns.

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

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

superman (noun)	leader (noun)
street name for lysergic acid diethylamide	a featured article of merchandise sold at a loss in order to draw customers
a person with great powers and abilities	a person who rules or guides or inspires others