what is the difference between first class and standard mail

what is the difference between first class and standard mail lies primarily in the speed of delivery and the cost. USPS First-Class Mail is a faster and more affordable service for sending smaller, lighter packages and letters, typically delivering within 1-3 business days. On the other hand, Standard Mail (also called Marketing Mail or USPS Retail Ground) is slower and used for bulk mailing, like catalogs or advertisements. Standard Mail is less expensive, but it takes longer to arrive, usually 2-8 business days, depending on the destination.