usps ground advantage cubic vs usps ground advantage refers to the comparison between two different shipping options offered by USPS. USPS Ground Advantage Cubic is a service that charges based on the cubic volume of a package, rather than its weight, which can provide cost savings for smaller, heavier packages. On the other hand, USPS Ground Advantage is a traditional ground service that charges based on the weight and size of the package. Both options offer reliable, economical shipping, but the cubic service is often more beneficial for shipping dense items, while the standard Ground Advantage service is better suited for lighter packages.