ups surepost vs usps priority mail UPS SurePost and USPS Priority Mail are both popular shipping services, but they differ in several key ways. UPS SurePost is a cost-effective service for ground shipments, where UPS handles the long-distance portion of the delivery, and USPS completes the last-mile delivery. USPS Priority Mail, on the other hand, is a more traditional service that provides faster delivery (1 to 3 business days) with reliable tracking and insurance. UPS SurePost may be slower but is generally cheaper than USPS Priority Mail.