"A full postcode identifies a group of addresses (typically around ten) or a major delivery point."

The United States can be more granular, as a "full postcode" equivalent in the United States is ZIP+4, which can resolve down to an individual building, mailbox, or person, depending on the characteristics of the location.

https://en.wikipedia.org/wiki/ZIP_Code#ZIP+4

And even for those where it isn’t one exact person/box there is a 2 digit delivery point code that often is included on the end.