Is gst is firm based tax, (vat as in earlier) or pan based?

 Is GST is firm based tax, as like,VAT  in earlier indirect Tax regime, where there were VAT No.and returns allotted to different firms as entity  or is GST is a PAN based? like a person heading different firms, but his PAN no.is quoted, so all purchases and sales of different firms to be combined under same PAN no.based GST registration No.