http://www.pcgamer.com/heres-what-the-evil-within-2s-difficulty-levels-change/

Now that The Evil Within 2 has launched, you may have already started your journey to save Sebastian’s daughter and fight lots of horrible things that give you life-long nightmares. If you’ve yet to begin your nightmarish adventure, however, then Tango Gameworks' explanation of the game’s difficulty levels might help start you off on the right foot. 

The Evil Within has four difficulty levels: casual, survival, nightmare and classic. You’ll be able to change your mind and pick a lower difficulty while playing, but you won’t be able to pick a higher one if that ends up being too easy, so it pays to know exactly what the differences are.