Why can a yellow street parking ticket and a white car-park ticket mean different things in Belfast?

Nidirect distinguishes the buff or yellow tickets used for on-street controlled parking from white pay-and-display tickets used for off-street car parking.

The colours help drivers avoid using payment evidence from the wrong type of location. In central Belfast a DfI-managed street bay may sit near a council car park, but they are not a single parking zone. Display the ticket where required and make sure the ticket or cashless session matches the place where you have left the car.