The difference is probably because the ticket from Backstage is just that - a ticket. What you bought from the regular ticket seller is most likely a ticket package with swag and maybe a dinner/party. Either that or they gave you a refund in error. When Backstage first put the Athens tix on sale, the prices were wrong. They took the sale down and corrected the prices. Unfortunately, it took them forever to refund the extra that was paid by the people who paid immediately.