insurance firm vs insurer

insurance firm and insurer both are nouns.

Word	Noun	Adjective	Verb	Adverb
insurance firm	Yes	No	No	No
insurer	Yes	No	No	No

As nouns, insurance firm and insurer are synonyms defined as:

insurance firm and insurer: a financial institution that sells insurance

Other synonyms of insurance firm include insurance company, insurance underwriter, underwriter.

insurance firm (noun)	insurer (noun)
a financial institution that sells insurance	a financial institution that sells insurance