Here is what Discmania says about the DD:
 
Step aside, it’s time to add some glide! An exciting addition to the Originals line ushers in a new era for long distance shots with the S-Line DD. As the name implies, DD stands for “distance driver” and that’s exactly what it’s going to offer. It provides the distance option when you really want to uncork one but still makes you feel like you’re throwing a controllable fairway driver and will be very complimentary to the other distance drivers in your bag.