Sony Computer Entertainment's John Smedley has given a refreshingly honest answer about the similarities between H1Z1 and Day Z. Speaking on Reddit he said: "How is this different from Day Z? - saw this a lot. Not going to give some politically correct dodgy b.s. answer. It's a 'survival in a zombie apocalypse' game. So is Day Z. They made a brilliant game (first I might add). They have a great vision for it and can count myself and most of the people on our team as fans and contributors."
He also expanded more on the overall vision for the game: "Long term we plan on making this about a persistent world with a big landscape with thousands of players. The way we would like to see this roll out is much more like players building small enclaves or pockets of territory and hold out against a legitimate zombie threat that's ever present while others go it alone taking their chances. These player built structures, forts and towns are one of the ways the players try to carve out some small space in a dangerous world". He also explained that the game will have a "deep economy that is heavily dependent on crafting", adding, "players will be able to become manufacturers, sell bullets, arrows, etc. The in-game economy will be entirely player driven".
More at the link.