H1Z1 was one of the early Battle Royale success stories. It captured audiences that were growing tired of DayZ and thrust them together in a more action packed, if still zombie-filled, setting. Since its heights a couple of years ago though, it has fallen out of favour with the wider gamer populace and new, more exciting games like Fortnite and PuBG have come along to take its place. In an effort to fix that, and help new players understand just what the game is all about, the developers have renamed H1Z1 to Z1 Battle Royale.
If this seems a little silly or opportunistic, you'd be right, but it also bears thinking that H1Z1 was a terrible name in the first place. It isn't remotely helpful in understanding just what the game is all about. It sounds more like a stock serial number for a robot vacuum than a zombie survival, Battle Royale game.
The new name isn't much better, but it does at least do what it says on the tin.
This is all the brain child of new developer on the scene, NantG, which has taken over production of the game and has launched a brand new season, promising a return to classic "King of the hill" gameplay from the earlier iterations of H1Z1. That will mean the re-introduction of old animations, vehicle mechanics, guns, and combat,according to PCGamer.
The UI has been overhauled and reverted and many of the changes to the main map have been removed. Essentially, Z1 Battle Royale is H1Z1 King of the Hill.
As for new stuff, there's a in-match mission system, new challenges on a daily and weekly basis.