A competitive online role-playing game (CORPG) differs from the standard massively multiplayer online role-playing game (MMORPG) in that they are less focused on the massive group experience. All outside areas are instanced, meaning that a player and his group are the only ones there, so that every player gets his or her own unique version of the game's story without the headache of killstealers or people disrupting the fun.
In Guild Wars, as opposed to one of NCSoft's other offerings, like City of Heroes, a player might roam the countryside with a group of 1 to 11 other heroes. In an MMORPG like City of Heroes, the group would be surrounded by other similar groups, all wishing to kill the same mobs and achieve the same goals, at the same time, in the same space. Guild Wars eliminates this scramble, letting players take the game at their own pace while playing player versus environment.
The competitive aspect of the name derives from the player versus player, guild versus guild, and an international war called the War of Worlds. In many respects, the PvP version of the game is a very different experience from PvE, using different strategies and playing styles to battle human opponents instead of the computer AI.