What does dedicated courier, integrated courier and manual management mean that appears as returnDeliveryType value when querying return request list?

The items and descriptions which can be put in returnDeliveryType are as in the following: 

<Delivery classification> 

• Integrated courier : Courier that a seller uses.
• Dedicated courier : Courier that Coupang uses. 
• Manual management  : CS agent manually enters return waybill number checking it with a customer or a courier.