Medicare Advantage 
A plan offered by a private company that contracts with Medicare to provide you with all your Medicare Part A and Part B benefits. Medicare Advantage plans are HMO’s, PPO’s, or Private Fee For Service Plans.  If you are enrolled in a Medicare Advantage Plan, Medicare services are covered through these plans, and are not paid for under original Medicare.

MAPD – (Medicare Advantage-Prescription Drug)
A Medicare Advantage plan that includes Prescription Drug coverage in addition to Medicare Part A and Part B.  This plan has a network, and functions like an HMO.

PFFS (Private Fee For Service)
A Medicare Advantage plan that has no network and accepts all providers who are approved by Medicare, and agree to accept the plan.

PDP – (Prescription Drug Plan)
A Prescription Drug plan is a stand alone plan that pays for prescription drugs.

SNP (Special Needs Plan)
A special type of plan that provides more focused health care for specific groups of people, such as those who have both Medicare and Medicaid, who reside in a nursing home, or who have certain chronic medical conditions.

Medicare Supplement (Medigap)
Medicare insurance sold by private insurance companies to fill the gaps in original medicare coverage.  In most states there are twelve standardized plans labeled A through L.  Medigap policies only work with the original Medicated plan.

You can access all of these and a great deal of additional information at www.medicare.gov.