Original medicare is a federal program available to people over the age of 65 or who are disabled. It consists of two parts - Part A, that covers hospital inpatient costs, and Part B, that covers outpatient medical costs. Both parts have annual deductibles, and Part B only covers 80% of medical expenses with no annual cap on your financial responsibility. Original medicare does not cover prescription drug cost.
Prescription Drug Plans
Medicare prescription drug plans are known as Part D. These plans are purchased through private carriers but regulated by the government. Once you become eligible for original medicare, you are required to obtain prescription drug coverage or risk paying a penatly in future years. Part D prescription drug plans can be combined with original medicare, or with original medicare and a medicare supplement, but are included with medicare advantage plans.
Medicare supplements, also known as medigap plans, pay some or all of the difference between your medical bill and what original medicare covers. These plans are known by their letters - Plan G, Plan K, Plan N, etc. Unlike the the other medicare options, medicare supplements have no government connection and can only be purchased from private insurance carriers.
Medicare advantange plans are known as a Part C plan. They are a combination of original medicare and additional coverage provided by a private insurer. They usually have a very low, or zero, deductible, but have co-pays for services that medicare supplements don't have. Medicare advantage plans include Part D prescription drug coverage, and even with that additional benefit, typically cost far less than medicare supplement plans.