The Original Medicare Plan includes Part A and Part B. Part A is considered to be hospital insurance and Part B covers outpatient costs. Part D, or prescription coverage, is not included. Part C, or an Advantage Plan, is essentially a health maintenance organization plan, or HMO plan. It usually includes medication or pharmacy coverage to some degree. Part C Advantage plans are accompanied by the same restrictions as HMOs. You must, in most cases, stay within their network of providers, hospitals and rehabilitation facilities. It can be extremely limiting and frankly (in my opinion as a nurse) extremely frustrating to navigate.