Final answer:
A co-pay is a set amount due at the time of service, while coinsurance is a percentage that the patient is responsible for, for certain services.
Step-by-step explanation:
A co-pay is a set amount due at the time of service for an office visit, while coinsurance is a percentage that the patient is responsible for, for certain services. For example, if a patient has a $20 co-pay for an office visit, they would pay $20 for each visit. On the other hand, if a patient has a 20% coinsurance for a certain service that costs $100, they would be responsible for paying $20 (20% of $100) and the insurance would cover the remaining $80. So, while a co-pay is a fixed amount, coinsurance is a percentage of the total cost.