Below is a article about Warhammer Online, Please enjoy it.

PvE, PvP and RvR  ( from : http://www.war-rvr.net ) 

PvP (Player versus Player) is a huge part of WAR, letting the players actually participate in and impact the great conflict of Order and Chaos as the six playable races clash. PvP areas are clearly marked and present in every map, letting the PvE-only players look across a bridge or into a fortress and see the bloody fun their PvP mates are having without them. (Hopefully encouraging PvE (Player vs Environment) players to participate)

Given there are PvP and non-PvP parts of every zone you won?t have to experience load times when entering a PvP conflict. All PvP is consensual in so far as you will be made aware of when you cross over into these zones.

You can gain Trophy Items from PvP to let you customize your armor for looks (and most likely not stats). For example, if you?re an Orc and you kill enough Dwarves, you could get a Dwarf skull which you could place on your shoulder spikes, on your belt buckle, or perhaps on a chain around you neck. According to Mythic, you?ll gain experience and items through PVP participation and become as advanced and as wealthy as players who exclusively hunt monsters and perform quests.

The End-Game content is a RvR (Realm versus Realm) campaign to take over enemy cities. If your side is totally outnumbered, as tends to happen in these types of games there could be PvP boosts to your alliance to try and balance it out, through stat bonuses or extra NPC spawns.

Even the PvE (Player versus Environment) aspect of the game follows the epic battle that rages on around you. Mythic had the foresight to eliminate the drudgery that plague a lot of MMOs. The pointless "grinding" of rats, fish and other lifeless creatures.  One example of how Mythic is merging the PvE aspect of the game and the RvR aspect that rages around you was as follows "As an Orc, you can expect to be repelling a beach landing of dwarves who are coming over a nearby waterfall using barrels."

The PvE quests you receive will also be in direct competition with the PvE quests assigned to your opposite faction.  In one example, "imagine a large amount of dwarves lay injured and immobile on the battlefield. The dwarves will try to heal other dwarves by giving them beer, while the orcs will be trying to kill them and take their beards."

According to Mythic they are planning on making it so that opposite alliances can?t communicate, although that may change, its doubtful.  Warhammer is known for its epic wars of light and dark, you wont see orcs holding hands with dwarfs.  Mythic has taken great care to follow GamesWorkshops IP, this means they will follow it to the letter, some changes may be made but they will be very minor and only to balance the game.  These changes will be aproved by GamesWorkshop from the go, and given GamesWorkshop?s lore and background is so deep with such a large following, they wont flex much.  The final product wont be a watered down version of their vision, it will be as accurate as possible.