A Medicare Advantage Plan (like an HMO or PPO) is another Medicare health plan choice you may have as part of Medicare. Medicare Advantage Plans, sometimes called "Part C" or "MA Plans", are offered by private companies approved by Medicare. If you join a Medicare Advantage Plan, you still have Medicare. You'll get your Part A (Hospital Insurance) and Part B (Medical Insurance) coverage from the Medicare Advantage Plan, not original Medicare.
In all types of Medicare Advantage Plans, you're always covered for emergency and urgent care. Medicare Advantage Plans must cover all of the services that Original Medicare covers except hospice care and some care in qualifying clinical research studies. Original Medicare covers hospice care and some costs for clinical research studies even if you're in a Medicare Advantage Plan.
Medicare Advantage Plans may offer extra coverage, like vision, hearing, dental, and /or health and wellness programs. Most include Medicare prescription drug coverage (Part D). In addition to your Part B premium, you usually pay a monthly premium for the Medicare Advantage Plan.
Source: 2019 Medicare & You, The Official U.S. Government Medicare Handbook