Settlement building is shared: what a friend places, moves or scraps appears in your game (as a plain copy; power and settler assignment stay theirs).
Friends' reloads and aiming down sights play on their stand-in, and their Pip-Boy light shows as a light on it.
Friends' melee swings and punches play on their stand-in.
Emotes: F9 points, F10 cheers, F11 claps, and your friends see it.
The shared world is saved on the host's PC and carried on next session: dead NPCs stay dead, loot stays taken, walls stand (bSaveSession, on by default).
A refused join now says which plugins differ ("Only you have: X.esp"), and the host can list cosmetic plugins that may differ (sIgnoredPlugins).
Friends' stand-ins are the right sex and body shape.
NPC gear is shared: the game that runs an NPC reports its weapon and armor, and the others dress their copy the same.
A friend's or NPC's automatic fire sounds like one burst, every shot heard; replayed automatic fire no longer loops forever.
A mirrored NPC takes off the armor its owner's copy doesn't wear.
Fixed a crash when a friend joined while their stand-in was still loading.
The free high-resolution texture pack no longer counts as a load-order difference.