The phrasing indicates a comparison between the data packet information for electronic messages and the physical container used for traditional postal correspondence. One is a digital construct carrying routing and delivery details for electronic messages. The other is the tangible wrapping protecting and addressing physical documents for postal services.
Understanding the distinction highlights evolving communication methods. Historically, the secure conveyance of physical documents relied on a physical container and address. Now, digital communications leverage similar constructs in their underlying protocols to deliver data reliably and securely. This shift demonstrates the increasing importance of efficient and secure data transmission in a digital age.