Medigap is Medicare Supplement Insurance that helps fill "gaps" in Original Medicare and is sold by private companies. Original Medicare pays for much, but not all, of the cost for covered health care services and supplies. A Medicare Supplement Insurance (Medigap) policy can help pay some of the remaining health care costs, like:

Medicare started offering insurance coverage for prescription drugs through Medicare prescriptions drug plans and other health plan options. Medicare's prescription drug coverage will typically pay over half of your drug costs, for a monthly premium. (see Medicare Part D)

Part B is Medical Insurance and covers physicians services, outpatient care, test, and supplies. (see Medicare Part B)