DDU stands for Delivered Duties Unpaid whereby your customer is liable for any duties, taxes, and Customs handling/processing fees incurred on the shipment upon receiving.
DDP stands for Delivered Duties Paid which means ESG pre-clears the duties and taxes on behalf of the merchant so your customer isn’t charged with any additional fees upon receiving the shipment. The Courier charges a DDP surcharge for managing this on top of every order; varies by Courier.