What is the difference between Arena Commander 2.0 and the large world release?
TL;DRThey are separate things: the large-world baby PU comes first, while Arena Commander 2.0 comes later as a refined mini-game and is described as no longer especially significant.
Really what you need to know is that they're different things. Large world is what we're calling the baby PU or the exoverse; it has a couple different names. They haven't settled on one perfect one yet. Arena Commander, Star Marine, we specifically built them into the world so they're games within a game. The baby PU is more of a giant stage for us to play with stuff. All of Star Citizen's parts are supposed to go in there and you'll watch them break and be fixed in real time. Whereas Arena Commander 2.0 will come a little bit once we've perfected the multi-crew stuff in the exoverse or whatever we end up calling it; it can then be, okay, well this is the mini-game in the Star Citizen universe where you use it. So I would say AC 2.0 is not especially significant anymore, it's just something that we will refine from the baby PU. But the great thing about the baby PU is it lets us do things like, okay, here's our mining mechanic, let's chuck that into the live server and see how it works. Here's our salvage, here's our exploration. Whereas that wouldn't necessarily make sense in Arena Commander, which is supposed to be an arena shooter.
So short version, you will see the baby PU large world map before you see Arena Commander 2.0. So you'll get to fly around in that before Arena Commander 2.0 comes out. They're now separate things. Similar, but separate. Related.