Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Chicago to New Plymouth as you normally would.
If you book a flight to New Plymouth from Chicago, you will be flying to New Plymouth, which is the city’s only airport. New Plymouth (NPL) is located 6.3 mi from the center of New Plymouth. There are 0 flights from Chicago to New Plymouth per day from 0 different airlines.
These are just IATA (International Air Transport Association) codes. They are used in aviation to identify and differentiate airports. That’s why a Chicago O'Hare Intl Airport to New Plymouth Airport flight would often be abbreviated as a ORD to NPL flight. Chicago Midway Airport (MDW), Chicago Greater Rockford Airport (RFD) are other airports near this flight route and their unique identifiers/IATA codes.