The Series X is more powerful than the Series S and as far as I know you have to buy all of the Series S games digitally
The Series S has no drive and has significantly fewer graphics, but the same processing power. The Series S also has less memory
No, the Xbox Series S and Xbox Series X are not the same console.
The main differences between these consoles are as follows:
The Xbox Series X is 300% more powerful than the Xbox Series S.
The Xbox Series X supports both digital and physical games (DVD's), while the Xbox Series S does not have a drive, so it only supports digital games
The Xbox Series X has around 800GB of free space, while the Xbox Series S has around 300GB.