Having bought two Diamond Sabers, I puzzled over this for a bit too.
The charger for the recharge port, and the one for just the batteries are indeed different, and I'd recommend getting both as well as a second (and maybe third) set of Trustfire or Xtar batteries through US when you get your saber. Selecting both chargers does indeed get you both. While both aren't technically necessary, having additional batteries available for hot-swap is great, especially if you plan on having the saber on for hours, such as for a con.
The charging port is also great if you plan on wall-mounting the saber, as you can just leave it plugged in and power the saber through the port, giving you the worlds coolest night light.