Medicare Advantage is a type of Medicare health plan offered by a private company that contracts with Medicare to provide you with all your Part A and Part B benefits.
Health Maintenance Organization (HMO) Plan
In most HMO Plans, you can only go to doctors, other health care providers, or hospitals on the plan's list except in an emergency. You may also need to get a referral from your primary care doctor to see other doctors or specialists.
Preferred Provider Organization (PPO) Plans
A Medicare PPO Plan is a type of Medicare Advantage Plan (Part C) offered by a private insurance company. In a PPO Plan, you pay less if you use doctors, hospitals, and other health care providers that belong to the plan's network. You pay more if you use doctors, hospitals, and providers outside of the network.
Medicare Special Needs (SNP) Plans
Medicare SNPs are a type of Medicare Advantage Plan (like an HMO or PPO). Medicare SNPs limit membership to people with specific diseases or characteristics, and tailor their benefits, provider choices, and drug formularies to best meet the specific needs of the groups they serve.
These definitions are directly from Medicare