employer vs boss

employer and boss both are nouns.

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

As nouns, boss is a hyponym of employer; that is, boss is a word with a more specific, narrower meaning than employer:

Other hyponyms of employer include hirer, master, mistress, padrone, Simon Legree, slave driver.

employer (noun)	boss (noun)
a person or firm that employs workers	a circular rounded projection or protuberance
	a person responsible for hiring workers
	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

employer (adjective)	boss (adjective)
	exceptionally good

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