Do Xbox One and One S play the same games?
This is called backward compatibility. With backward compatibility on the Xbox Series S: You can play all digital Xbox One games. You can play a few digital original Xbox and Xbox 360 games.
Can Xbox S and Xbox One play together?
Yes. If a game is available to play on both Xbox Series X|S and Xbox One, you'll be able to play multiplayer with gamers from both systems. Note Cross play is at the publisher's discretion, so there may be examples in which players on Xbox Series X|S won't be able to play cross platform with Xbox One players.
Can you game share between Xbox One and Series S?
The Xbox One was one of the first consoles to fully embrace this feature, and the simple process allows you to give a person you trust access to your library of downloadable games. This feature would carry forward to the next-generation Series X and S consoles as well.
Can I play on Xbox One and Xbox Series S with the same account?
You can sign in to multiple devices at once, such as an Xbox One console, Xbox Series X|S console, mobile device, Windows device, or through cloud gaming. However, there are exceptions to this rule.