An HRA or Health Reimbursement Account is an arrangement between the employer and employee, where the former reimburses the latter for specific medical expenses, on completion of a filing process. A well-planned Health Reimbursement Arrangement (HRA) facilitated by your employer can definitely help reduce the cost of overall healthcare spending. It only covers the cost of deductibles and coinsurance.
An MERP, on the other hand, is more flexible. Employers and employees can create multiple member plan designs with multiple benefits, with the employee being directly reimbursed, tax-free, for all expenses (up to a pre-decided amount for pre-qualified services/products). While the benefits for the employees are diverse, the employer also benefits from a lower cost of group health insurance. Employers can also buy one single MERP plan and create multiple funding arrangements and benefits designs. They can also assign different levels of contribution for each employee.