Originally, KDP was for Kindle eBooks, while CreateSpace was for paperbacks (and videos and even audio).
However, in recent months KDP has added print-on-demand publishing for print books. It has slowly evolved, and now matches CreateSpace in terms of quality, service, and prices (with a few subtle exceptions). Overall, in a few ways, KDP’s print-on-demand is a little above and beyond CreateSpace (it wasn’t originally, but now that it has finished evolving, it is now).
Our authors should have received an email about this. Go sign in to your KDP account asap.