List five differences between tricare extra and tricare prime insurance plans

1. Tricare Prime is cheaper than Tricare Extra;2. Tricare Prime beneficiaries can only use Military Treatment Facility, 
    whileTricare Extra beneficiaries can use any civilian healthcare provider
    payable under Tricare rules;
3. Beneficiaries (retirees) of Tricare Prime have to pay a small co payment 
    for while Tricare Extra (retirees) do not.
4. There is an annual enrollment fees for military retirees in Tricare Prime, 
    but there is no annual enrollment fees for Tricare Extra;
5. Tricare Prime is a Health Maintenance Organization (HMO) while Tricare
    Extra represents a Preferred Provider Organization (PPO);