insurer vs insurance firm

insurer and insurance firm both are nouns.

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

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

insurer and insurance firm: a financial institution that sells insurance

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

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