Spend Analysis reports take information extracted from your Detailed Billing Reports and aggregate it for any time period specified. Summary and Detail reports illustrate all the costs associated with a particular AWS service, while Static Reports take a snapshot of your service deployment and history in order to make an estimate of future usage.
Summary and Detail Report
Spend Analysis Summary and Detail reports break down all the costs for relevant AWS services, including EC2, RDS, S3, ElastiCache, WorkSpaces, and more. When you need more than a quick synopsis from the Summary reports, the Detail reports (where available) will provide data for storage, network, cost, CloudWatch, etc.
Static Reports take a fixed view of your service at one point in time, like a snapshot. From that static view, they calculate the estimated cost of running those services for the next month. These estimates are based on looking at past usage, reserved usage, current pricing, and other factors. They only factor in the cost of running the service itself and do not factor in any other costs such as other dependent services. However, Static Reports can provide valuable warnings for overspending and under-utilization on deployments that are stable over longer periods of time.