USPS Priority Mail vs First Class
USPS Priority Mail (formerly called Express Mail™) is ideal for shipments that can’t be delivered within four hours of pickup. Although it has a delivery guarantee, the service offers no additional insurance or tracking features.
First Class mail includes more benefits than USPS Priority Mail, such as tracking details and up to $50 in insurance coverage. It also has a quicker turnaround time (2-day guaranteed). And while there are restrictions on weight and size of contents, first-class mail is often less expensive than priority mail — so shipping costs might actually work out cheaper with this class of mail plus the other added features!