PvE is a playstyle of Zombie Survival differing from PvP. The zombie team is exclusively controlled by AI, with any humans killed being moved onto the spectator team (as opposed to joining the zombies such as in PvP)
PvE can be played with up to 4 humans who may fight up to 10 bots at a time, in contrast to PvP which can support up to 32 humans.
PvE, unlike PvP, focuses on a few individual players and close teamwork, rather than on the masses and the entirety of gameplay. Maps on PvE are often smaller than PvP and staying within a small area is intended.