Offer refers to the terms of an insurance contract as proposed by one party (the potential insurer)...
To accept is to agree to insure.
An insurer accepts a risk when an underwriter or agent agrees to insure it, and the essential elements of the insurance contract are known and agreed to by the parties to it. Even though a policy has not been issued, once the risk is "accepted," the insurer is obligated to pay a loss that occurs subject to the terms and conditions of the coverage agreed upon.
Offer refers to the terms of an insurance contract as proposed by one party (the potential insurer)...