The difference between a USPS regional origin facility and USPS regional facility is that the USPS Origin Facility is the facility that your packaged has originated from.
For example the shipper takes your package to the local post office to drop off the package and have it shipped out then that place would be the USPS regional Origin Facility.
As for the USPS regional Facility that is the facility that is closer to your location and is the facility that your packages travels to after it has left the local post office or origin facility where the shipper dropped off the package.
There's more than one USPS regional facility that your package may get too before it gets to your destination.
It goes to one USPS regional facility then another USPS regional sorting facility where it then gets to the destination.