https://www.gamespot.com/articles/what-does-xbox-one-x-enhanced-really-mean/1100-6453485/

Microsoft's Xbox One X represents something somewhat new for the company as it relates to hardware. The console is not a replacement for the current Xbox One. It's not a generational change in the way that Xbox One was to Xbox 360. The Xbox One X will play all of the games available on Xbox One and it works with the controllers you may already have. Microsoft is aware that messaging is important, and now the company has released a video in which Xbox's Albert Penello and Major Nelson explain some of the big points.

Starting off, Penello stressed that every game on Xbox One will work on Xbox One X. This includes titles bought at a physical retailer and digitally. The Xbox One X also features backwards compatibility support for Xbox 360 titles, and Original Xbox games at some point further down the line. Also, your Xbox One controllers work on Xbox One X.