A booking can name one airline while the aircraft belongs to another. That arrangement affects service, baggage and responsibility in ways the confirmation rarely spells out.
The marketing carrier is not the operator
In a codeshare, one airline markets seats under its own flight number on a service physically operated by another. The passenger books with the first and flies with the second.
Confirmations state this as an operated by line, usually in small type. The flight number in the booking may not appear on any airport display.
Finding the check-in desk therefore requires the operating carrier's name. Passengers looking for the marketing airline's counter are in the wrong terminal at some airports.
The onboard product belongs to the operator
Seat pitch, catering, entertainment and cabin configuration are whatever the operating airline provides. Expectations set by the marketing airline's branding do not carry across.
This matters most where the two differ in positioning. A premium carrier's code can appear on a service operated by a low-cost or regional subsidiary.
Seat selection is often restricted for codeshare passengers. The operating carrier controls its own seat map and may release only part of it to partners.
Through-checking is the practical benefit
The main advantage is a single ticket covering the whole journey. Baggage is checked to the final destination and connections are protected by the airline that sold the itinerary.
A missed connection on a through ticket becomes the airline's problem to solve. Rebooking happens without a new purchase, which is the substantive difference from separate tickets.
Minimum connection times are calculated for the combination. A codeshare itinerary will not sell a connection the system considers too tight.
Loyalty accrual follows separate rules
Miles and status credit usually depend on the operating carrier and the fare class, not on whose code is on the ticket. Some fare classes earn nothing on partner-operated flights.
Lounge access and priority services are provided by the operating airline at the departure airport. Entitlements granted by the marketing carrier may not be recognised there.
Checking accrual rules before booking is worthwhile for anyone chasing status. The same journey can earn very differently depending on which code was purchased.
Where responsibility sits when things fail
Passenger rights regulations generally attach to the operating carrier, which is who owes compensation for delay or cancellation. Claims filed with the marketing airline get redirected.
Customer service is split in practice. Changes to the booking are handled by the airline that issued the ticket, while airport disruption is handled by the operator.
Knowing which airline holds which role before travelling saves considerable time. The distinction only becomes visible at the moment it matters.