So, I keep hearing that Amazon will shutter CreateSpace, their separate self-publishing arm for physical "printing" (they do CDs and DVDs as well as paperback books) and make everyone use KDP, which now has an option to "Create Paperback."
In the past I stuck with CreateSpace because it had some functions not offered in KDP Print but it looks like those are pretty well accounted for now. In additon, if the book already exists in CreateSpace, Amazon has made it very easy to move the book over to KDP. When you click the link in the KDP database (illustrated here with a title I have not yet published in print) to create a paperback, you get a form to fill out that's partly filled in from the Kindle version.
If you answer yes to the question "Have you published this book on CreateSpace?" it gives you a place to enter the ISBN (whether it's an ISBN CreateSpace assigned or one you own). Once you do that, KDP retrieves the PDFs of the interior and the cover so you don't even have to load them again. One quirk I found was that if you had loaded your book to CreateSpace but didn't actually publish it, this process won't work; you need to complete publication on CS, and then move the book over to KDP Print. You still have an option to get a draft copy from KDP if you want to be sure. I notice that instead of merely marking "proof" on an inside page, KDP puts a Not for Resale banner on the draft copy's cover,
Once the paperback version exists in KDP, the entry for that book includes a separate set of options for that version. The menu there is where you can order author copies and make changes, if needed.
Anther advantage is, your print sales (once they are shipped) show up in the same Sales Dashboard bar graph as your Kindle sales. Free ebooks "sales" are blue, regular ebook sales are gold, and print sales are gray. The Month to Date spreadsheet-style chart has a button to select paperback or ebook format.
The final advantage is, the paperback version of Alien Vows was linked to the Kindle version within 24 hours, without my doing anything to request it.
At present, I have three titles in KDP Print and three still in CreateSpace. When I get ready to publish my other five ebooks in print, I will start with KDP.