I is a f2p generic pay-to-win game. The other is a b2p non-pay-to-win game.
Outside of the MOBA genre GW2 has the best PvP out of any mmorpg. This is because the PvP is balanced in terms of who has access to what. In structured PvP in heart of the Mists everyone has access to the same items, same traits and same stat customization options.
The meta is not perfect however, the game currently has too much sustain and too many damage avoidance methods, as a result the best builds utilize condition damage or AI pets/phantasms/minions for passive persistent damage. A lot of people are unhappy with the current meta, but the devs have recently been taking notice of the community's woes and are making changes (granted at an excruciatingly slow pace).
Currently there is only one mode for PvP matches, that is domination Capture-the-Point.
As for PvE and WvW, they are not my cup of tea, but others may like it. You don't need to do any PvE or WvW content in order to PvP. In heart of the Mists everyone is at lvl 80, even if your PvE character is lvl 2.
WvW is kind of softcore PvP because gear and levels are a factor and more often than not it is Zerg v. Zerg gameplay. The success of your realm is mostly determined by whether or not you have an active healthy WvW-ing population around the clock. If your realm does not have a solid night crew then the other realms will just cap everything overnight.