The ToH has defined 3 (4 if one includes Battery Powered Travel Routers) classes of devices. Looking at some of these it appears that the difference are based upon the intended use from the factory and physical form factor.
Range Extender - Plugs into the wall and connects wirelessly to the main router (Repeater bridge). The ones in the ToH that show support also have an Ethernet port intended as a LAN port.
Wifi AP - Mostly looks like a router, and connects to the router via an Ethernet cable and offers an additional SSID. Probably connects to the wall with a 12v or 5v transformer. Has one Ethernet port.
Travel Router - Small portable device configured as a router and typical offers some additional features like multimedia sharing. May have a switch which supports Router\AP\Bridge functionality. Runs off 5V usb or battery. Has 1 or 2 Ethernet ports. If 2, one is LAN and the other WAN.
Can anyone confirm that when flashed with LEDE that these devices have the same or different default configurations? I believe that the Travel Routers with only a single Ethernet are all delivered as a "Router" with only a LAN interface, or basically default with a single interface.
This is relevant to the authoring of the installation instructions. If these are all the same or even 3 different configs by class then we can document this centrally. If this is device specific it would need to be documented in the individual device pages.
I don't think that anybody can confirm that without looking into each device separately, as the configs are defined by platform and are device-specific.
But e.g. for ar71xx, the network config seems to be "lan-only" for some 60 devices that likely fall into these categories: (From that list I have MR3020 which is travel router, but I haven't actually tried LEDE in it)