employer vs hirer

employer and hirer both are nouns.

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

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

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

employer (noun)	hirer (noun)
a person or firm that employs workers	a person responsible for hiring workers