A deductible is what you pay before your plan starts paying for covered services, a copay is a fixed amount you pay for a visit or service, and coinsurance is a percentage of the allowed amount you pay after coverage applies. Dialysis bills can involve more than one of these, especially when labs, physician services, supplies, and medications are billed separately.
If you are seeing confusing charges, ask for an itemized explanation of benefits (EOB) and confirm whether each charge was processed in-network.