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

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:

Part A is Hospital Insurance and covers cost associated with confinement in a hospital or skilled nursing facility. (see Medicare Part A)