The Production Environment
The Prod environment is structurally identical to the Dev and Staging environments.
Prod environments are usually of size Medium or Large, which gives them high-availability failover.
You can choose Blue/Green or In-Place deployment for each Ocean environment. For a Prod environment, the deciding factor will likely be how often deployment takes place. The more often, the likelier it is that you will be using In-Place deployment, especially when using a Continuous Deployment workflow. If, on the other hand, your workflow is Continuous Delivery (meaning deployments have to be vetted manually), and you release more seldom, Blue/Green might be more suitable. It's entirely up to you.
In Prod, services use separate RDS DB instances to facilitate easy backup and snapshotting. (In Dev and Staging, only one RDS DB instance per environment is used.)