Amazon Web Services (AWS) has made some significant changes to the fees it charges for reserved EC2 instances. First, the cloud computing services has eliminated the light, medium and heavy utilization tiers. There is now just one price schedule for all reserved instances.
Second, AWS no longer requires customers to pay the entire fee for reserved instances upfront. Customers who do pay in advance will receive the deepest discounts, followed by customers who make partial advance payments. But even customers who choose not to pay anything in advance will see significant savings over EC2's On Demand pricing.