if something is exempted than gst paid on input used in production or provision of that good/service go waste.....nothing is refunded by government..........
on the other hand goods which are 0 rated (like export and sale to sez), any gst paid on input is refunded by government....
that's why exports (and sales to sez) are 0 rated because government wants to promote exports and by providing refund of input goods become competitive in international market.....