What is the difference between a Medicare Advantage (Part C) plan and a Medigap policy?

Medicare Advantage plans, also known as Medicare Part C, are Medicare plans that bundle (group together) Medicare Part A, Part B, and usually Part D coverage. Medicare Advantage plans are managed by a private insurance carrier (e.g. Aetna or Blue Cross Blue Shield), instead of CMS. 

Medigap policies, also known as Medicare supplemental insurance plans, are optional add-ons for clients who have Original Medicare. Medigap policies help to cover some or all of the gaps in Medicare Parts A and B coverage but do not include prescription drug coverage. 

Clients with Medicare Advantage plans cannot purchase Medigap policies.