Short answer: A copay plan charges fixed dollar amounts for common services (like office visits and prescriptions), giving predictable point-of-care costs, usually in exchange for a higher premium than a high-deductible plan.
A copay plan applies set dollar copays to everyday services, for example a flat fee for a primary care visit or a generic drug, so members know their cost up front. Bigger-ticket services like hospitalization or surgery may still run through the deductible and coinsurance. Copay plans carry higher premiums than high-deductible plans, which can pay off for people who use care regularly. The out-of-pocket maximum still caps total annual exposure.