Standard vs Expert Sphere Grid

The International version of Final Fantasy X gives the option at new game to choose between Standard and Expert Sphere Grids. (This also applies to the HD remaster versions.)

It appears that the Standard Sphere Grid is larger though. Does that mean that the theoretical maximum stats of characters on the Standard Sphere Grid would be greater than the theoretical maximum stats of characters on the Expert Sphere Grid?

If that is the case, then what would be the reason for playing using the Expert Sphere Grid?

Solution 1:

Does that mean that the theoretical maximum stats of characters on the Standard Sphere Grid would be greater than the theoretical maximum stats of characters on the Expert Sphere Grid?

Yes, by ~70 spheres, if I recall correctly.

If that is the case, then what would be the reason for playing using the Expert Sphere Grid?

In the Expert Sphere Grid, all your characters start out very near the center, allowing you to choose different paths fairly early on, rather than having set pathways that you'd need high-level Key Spheres to break out of.