Xbox Series S or X? What's the difference?

Basically as the title says.. I have the xbox one. Want to upgrade to S or X but not sure which. I only really play EA FC or NHL, GTA 6 when that comes out too, not much else at all.

Am I right thinking the main differences are the storage size and resolution? And the X is 4k and S is 1440p but how much difference actually is that?

The price difference is £200 as well so is it worth just getting the S?