FTDI cables confusion
You're going to have to look at the specific XBee. An FTDI cable is just typically an adapter that can mate a USB connection to a UART breakout. The absolute minimum for a UART is a +V, GND, TX and RX line (looks like that's what you have). Something like an Arduino will also need a DTR and a CTS line (the other 2 of the 6 you're looking at). The CTS isn't necessarily used, but the DTR line is typically used to trigger a reset for programming. 

FTDI is actually a company that makes the USB chip. SparkFun has a number of these, and they call them FTDI adapters (not sure if they started the naming), which is where I've seen them before.

If you're using this just for communication, either should work fine. 

NOTE make sure the voltage is correct. That looks like it breaks out a +5V line. If your xbee needs 3.3V, you're going to release all of the magic smoke.