insurance company vs insurer

insurance company and insurer both are nouns.

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

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

insurance company and insurer: a financial institution that sells insurance

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

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