The move to USB 3.0 only affects charge rates connected to a PC.
2.x is limited to 500mA while 3.x is 900mA I think.
Both standards use 5V, but 2A AC chargers often run a bit higher at 5.3V. The chargers don't directly adhere to either USB spec and basically trigger fast charge the same as before, by shorting out or putting a fixed resistance between the data pins.
My old HP TouchPad USB 5.3V/2A charger with 2.0 cord charges my Note 3 just as fast as the Samsung 5.3V/2A adapter with USB 3.0 cord does.
If you look closely, you'll notice that the "USB 3.0" Samsung charger doesn't actually have the extra 3.0 pins, it uses a 2.0 port. That's because for pure charging devices the standard doesn't matter, only the current and voltage rating and that it shorts the data pins.