Priority Mail and Priority Mail Express represent the best in USPS shipping.
U.S. Postal Service Priority Mail and Priority Express Mail both get your items to their destination fast, and they both offer features like tracking numbers and a standard level of insurance. The main differences between the two are delivery times and dates. Priority Mail Express gets your letters and packages there faster and can deliver seven days a week, but you'll pay extra for those services. The other important difference is that Priority Mail Express is a guaranteed service.
Summary of USPS Priority Mail and Priority Mail Express
Priority Mail is the United States Postal Service's standard air service. Packages should arrive at their domestic destination within 1-3 business days. Transit times vary depending on how far the package is going from its origin. However, it's vital to keep in mind that this is not a guaranteed service. There's no refund or anything that can be done if it doesn't make it in time.
Priority Mail is the less costly option of the two. There are also more rate and package options, including several Flat Rate box and envelope sizes, Regional Rate, weight-based rates, and dimensional-based rates.
Priority Mail Express
It used to be known as Express Mail; Priority Mail Express is USPS's fastest shipping service. Depending on the distance a shipment must travel, USPS will make a service commitment of 1 to 3 business days for domestic shipments.
Overnight scheduled delivery by 10:30 am also available to most U.S. addresses, including PO Boxes. As of 2020, the fee for this service is $5.00 per package.
Most importantly, this is a guaranteed service. If the package isn't delivered by the guaranteed delivery date, you can apply for a refund of the postage paid. Refunds claims must be filed at the Post Office, where the package was dropped off the package. We handle claims on behalf of our clients for them.
Priority Mail Express is limited to a few Flat Rate envelope options and weight-based rates.