FSNO is a "subfeed" of FS Southwest...basically a subsidiary or division. When there is no original NOLA programming scheduled, the channel shows whatever is on FSSW. On DirecTV, we get all of the subfeeds on a different channel number with the main FSSW feed on one. So, when there is no FSNO original programming on, 678 and 678-1 are basically "off air" with all programming on 676 which is the main FSSW feed.
Kind of confusing, but you get the hang of it after a while. It was the same way with FS Houston and is with FS Oklahoma.