Long Polling
https://www.pubnub.com/blog/2014-12-01-http-long-polling/
Websocket
https://en.m.wikipedia.org/wiki/WebSocket
Since that is a newer setting, which you use is probably dependent on you connection. If you aren't having problems with Live connections then you are probably fine keeping the default.
We are offered a choice between secure long polling and secure websockets. Can someone explain the difference and when it might be appropriate to choose one over the other?