Final answer:
A CPN (coupon) represents a fare component, while a segment represents each individual flight in a journey.
Step-by-step explanation:
In the context of airline reservations, a CPN (coupon) refers to a specific portion of a ticket that represents a distinct fare component within the overall ticket. It is used to calculate the total fare for a journey based on factors such as travel class, time of travel, and flight duration.
On the other hand, a segment refers to each individual flight in a journey. It is a single part of the complete itinerary from the departure airport to the final destination. Segments are used to determine factors such as the number of flights and the specific routes taken.
To summarize, a CPN (coupon) represents a fare component, while a segment represents each individual flight in a journey.