Below is a video showing the differences between ad-free Kindles and ad-supported Kindles, also called Kindles with Special Offers.
Ad-supported Kindles cost $20 less than ad-free Kindles. If you get an ad-supported Kindle you can unsubscribe from Special Offers at anytime by going to the Manage Your Devices section of your Amazon account and paying $20 to remove the ads.
You can also contact Amazon support about removing Special Offers and sometimes they will remove them for free, but not always—it seems to depend on the mood of the customer service rep.
Amazon recently changed how ads display on ad-supported Kindles since the 5.13.7 software update. Now ad-supported Kindles only show ads on the sleep screen when the device is turned off. They used to also show a banner ad at the bottom of the homescreen and library view, but that is no longer the case with the new user interface. Now ad-supported Kindles only show ads on the sleep screen when the device is turned off.
The biggest usability difference with ad-supported Kindles is they require an extra step every time you turn them on. You have to swipe the screen to unlock the Kindle, even if you spent extra on a cover with auto-wake functionality.
Ad-free Kindles do not require swiping the screen to turn them on. Hitting the power button or opening the cover will take you right back to where you previously left off.
Instead of showing advertisements, ad-free Kindles have the option to display the bookcover of your most recently read book on the sleep screen when the device is turned off, or you can turn cover view off in settings and view random screensaver images instead. If you’re using a Kids Kindle or Kids Mode on a regular Kindle it will show kid-friendly screensaver images when cover view is turned off.