With an indie, as soon as you upload the file, you can sell it. With KDP, you’ve got to wait until it appears on Amazon.
Web designer and writer, Paul Jarvis has self-published three books and has sold close to a total of 10,000 copies. With two of the books he used Gumroad and Sellfy which are indie sales platforms (digital goods e-commerce services). His latest book was on Amazon’s KDP Select platform.