It's different to Dead Island, as a quote from the wiki page: "Dying Light started out as a Dead Island sequel, but Techland made it a complete new video game because it would contain brand new features, such as a massive open world, new zombies, real time day/night cycle, better graphics, new game mechanics, and much more." Sounds promising if they deliver! :D
It's set for realease in Febuary 2015. :)