Final answer:
The four main HMO models differ according to payment arrangements with physicians. In a fee-for-service system, providers are reimbursed based on the cost of services. In HMOs, providers are reimbursed based on the number of patients they handle.
Step-by-step explanation:
The four main HMO models differ according to payment arrangements with physicians. In a fee-for-service health financing system, medical care providers receive reimbursement according to the cost of services they provide. However, in health maintenance organizations (HMOs), medical care providers receive reimbursement according to the number of patients they handle. This payment arrangement incentivizes providers to allocate resources between patients who receive more or fewer health care services.