The biggest difference between PPO and POS plans is generally flexibility. Both plans cover you whether you use providers and facilities in or out of the network. However, a POS requires you to have a primary care physician and get referrals from them if you want to see a specialist or anyone else. PPOs don't. Costs are another consideration. PPOs tend to be more expensive than POS plans—the premiums are higher and they usually come with deductibles that must be met before your coverage begins.