priority mail vs regular mail compares two different types of mail services offered by USPS. Priority Mail is a faster service that includes delivery in 1 to 3 business days, while regular mail, also known as First-Class Mail, is a more economical option that typically takes 3 to 5 business days for delivery. Priority Mail comes with additional benefits such as tracking, insurance, and flat-rate pricing for certain packages. Regular mail, on the other hand, is often used for letters, postcards, and smaller packages. When choosing between these two services, it’s important to consider both the delivery speed and the cost.