boss vs leader

boss and leader both are nouns.

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

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

boss (noun)	leader (noun)
a circular rounded projection or protuberance	a featured article of merchandise sold at a loss in order to draw customers
a person responsible for hiring workers	a person who rules or guides or inspires others
a person who exercises control over workers
a leader in a political party who controls votes and dictates appointments
a person who exercises control and makes decisions

boss (adjective)	leader (adjective)
exceptionally good

boss (verb)	leader (verb)
raise in a relief