Im new to the game. So im wondering what the difference between PVP and PVE gear? ANd why is it a bad idea to go into a WZ with PVE gear on?
PvP gear has a stat called Expertise. This is a common theme in other MMO's (notably World of Warcraft).
Expertise increases your damage versus players by a % and reduces damage from other players by a % and increases the amount you get healed by a %.
PvE gear doesn't have this stat (as it's useless in PvE). So imagine a PvP geared person going up against a PvE geared person, The PvPer will have a bit less of their primary stat than the PvE, but they'll be doing ~30% more damage, be taking ~20% less damage and getting healed ~15% more than the PvE character. It's a crippling difference.
Keep in mind, this doesn't apply in the 10-49 PvP bracket (well, it does, but the amount of expertise you can get pre-50 is really marginal and doesn't make much difference)