Original Medicare and Medicare Advantage plans share healthcare costs with patients through premiums, deductibles, copayments, and coinsurance. Premiums are monthly fees, deductibles are fixed amounts patients pay before coverage starts, copayments are fixed amounts paid per service, and coinsurance splits costs as a percentage between patients and plans. It is important for Medicare enrollees to understand these terms and how they vary between plans during open enrollment to estimate their potential out-of-pocket costs and choose an affordable option based on their healthcare needs.