It really depends on the company, each of their policies are different. Usually
HMO vs.
PPO has little to do with prescriptions, it has more to do with in-network issues. You may also have a secondary insurance policy for prescription drugs, which is very common (I have United HealthCare, but my prescriptions go through ExpressScripts). A lot of insurance policies will farm out things like prescriptions and mental health benefits to second companies.