https://www.pcgamer.com/fallout-76-survival-mode/

We now have a better idea of how Fallout 76's new PvP mode, which Bethesda has been teasing for a while , will work. It's called survival mode, and it's separate from the main game (which is now being called 'adventure mode'). A beta of survival mode is planned for March, though Bethesda says it may need more time to develop it, so that's not set in stone.

Here's how it will work when it does arrive: When you login to play Fallout 76, you'll be given a choice between adventure mode (the original game) or the survival mode beta. "The same quests, events, and story that you’re used to in Adventure mode will all remain available in Survival," Bethesda's post reads, "but you’ll have to navigate them under the ever-looming threat of hostile dwellers who may be hiding just around the corner."