what is the difference between priority and express mail

what is the difference between priority and express mail refers to the varying levels of delivery speed offered by USPS. Priority Mail provides 1-3 day delivery, while Priority Mail Express guarantees overnight delivery, even on weekends and holidays. The express service is faster, more reliable, and more expensive than standard priority mail, which makes it suitable for urgent shipments. Both services offer features like tracking, but Priority Mail Express also includes a money-back guarantee if the delivery is not made on time.