Need some clarification regarding futures websocket base urls

I have a some questions regarding the base urls in the Binance Futures docs.
I understand that there are two base urls that can be used for connecting to the server: wss:// (base url1) and wss:// (base url2). It is quite clear to me how to use the first base url for opening connections and live-subscribing (open a connection to wss:// then send the SUBSCRIBE message, etc.) or how to use it for opening a stream connection directly using a streamName.
But I am somehow at a loss about what to do with the second base url:
Is it only used for user data or also for all futures market streams?
I can connect directly by providing the listen key and stream name in the websocket url when opening a connection for a single or multiple streams. But how do I do live subscribing having a valid listen key? (.i.e. opening a connection then sending the subscribe message) Should it even be done like that?
It seems you have to implement two different logics depending on which base url you use.
Thanks for shedding some light on this.

Regarding the distinction between the two domains, a listenKey is required forwss:// require a listenKey , whereas it is not necessary for the other domain.
Apart from that, everything else is similar.
Please be aware that wss:// will be retired soon. You can find more details here: Binance API Documentation