HBO MAX isn't so much a live streaming service, but just a streaming TV service.
There's AT&T TV, AT&T TV NOW, AT&T Watch TV and now HBO MAX.
As AT&T is investing quite a bit of money into HBO MAX and its original content, to keep users on-board.
As mentioned, HBO MAX is a new service from AT&T that combines all of the HBO originals with the entire library from WarnerMedia.
Basically, HBO MAX takes everything that HBO has, and everything that's under the WarnerMedia umbrella and puts it into one streaming service, for the same price as regular HBO.