Those are usually the prefixes for interfaces which are not quite the same thing as networks. An interface is the surface that connects some device to a network. For example if your router treats its WLAN and its wired network as a single network (i.e. each thing on WLAN can see everything on wired and vice versa) then a specific device might still have a wlan1 and eth1 interface, each one reaching the respective physical network device, while being in the same network.
"One network" here really only means "something can successfully route between all the devices".