Earlier quoted context omitted.
Being able to use the same syntax for code and data is no small thing. This aspect alone puts it above JSON. That, and for most LISPS, S-expressions have a broader vocabulary than JSON (symbols, complex numbers, etc.).
JSON also has hash tables (which they confusingly call “objects”), which sexps do not. One may argue that one is or isn’t slightly better than the other, but the point was that they are very close.
JSON is just arrays, objects, bools, numbers, strings, and null.
How are they "close"?