What's the difference between HMO's and PPO's?

OK...Here's the deal. Basically what everyone else already said is technically correct. However, consider this: In an HMO the same people in charge of providing you with health care are also in charge of reducing the COST of providing such care. BIG CONFLICT OF INTEREST. I can point you to dozens of horror stories where care at an HMO suffered GREATLY due to cost concerns. Whereas with a PPO you have two separate entities that provide care and manage the cost of care. Most HMOs go financially insolvent at some point as well. So pick a PPO or Point of Service plan. Stay away from HMOs.