Well once you're able to check the tracking info from UPS it will have a "Shipped By" section on the right. If it says UPS SurePost it will be sent by UPS to the main USPS location for you and then delivered by USPS. If it says UPS Ground it will be handled by UPS all the way to you. I've had experiences where UPS was already coming my way and would deliver it themselves instead of dropping it off to USPS to handle it.