A Medigap policy is a health insurance policy sold by private insurance companies to fill "gaps" in Original Medicare Plan coverage. Every Medigap policy must follow federal and state laws designed to protect you, and they must be clearly identified as “Medicare Supplement Insurance.” Insurance companies can sell you only a “standardized” policy identified in most states by letters A through D, F through G, and K through N. All policies offer the same basic benefits, but some offer additional benefits so you can choose which one meets your needs. In Massachusetts, Minnesota, and Wisconsin, Medigap policies are standardized in a different way.
Medicare Advantage Plans are health plan options that are approved by Medicare but run by private companies. They are part of the Medicare Program, and sometimes called "Part C." When you join a Medicare Advantage Plan, you are still in Medicare. (see Medicare Part C) With Medicare Advantage Plans: