A USPS origin facility is a USPS facility where the package or mail originated from gets sent to and sorted.
For example if you ordered something from California then the USPS origin facility would be the facility in California where the package gets first sent to.
Then the Origin facility then sends the package to other distribution facilities and then it gets to the USPS destination facility.
The USPS destination facility is then the USPS facility that is located either in your state or near your state where the package is then to be loaded onto the delivery vehicle to be sent to your door or delivered to your local post office.
A USPS network distribution center is a sorting facility where packages and mail go through.
When you have something shipped through USPS the package goes to a local post office and then gets loaded onto another truck and goes to a USPS network distribution center.
The USPS network distribution center then sorts the packages and then places the packages onto another truck or airplane to arrive at another USPS network distribution center.
The USPS network distribution center is a massive building with thousands upon thousands of packages being sorted daily and even through the night.
The USPS network distribution center has conveyor belts and computer systems to scan and sort the packages.
The USPS network distribution centers are always open and operating even when your local post office is closed.