As per the Kubernetes documentation there is 1:1 correspondence between Deployment and ReplicaSets. Similarly depending on the replicas attribute , a ReplicaSet can manage n number of pods of same nature. Is this a correct understanding ?
Logically (assuming Deployment is a wrapper/Controller) I feel Deployment can have multiple replicaSets and each replicaSet can have multiple Pods (same or different kind). If this statement is correct, can some one share an example K8S template ?
1.) Yes, a Deployment is a ReplicaSet, managed at a higher level.
2.) No, a Deployment can not have multiple ReplicaSets, a Deployment pretty much IS a ReplicaSet. Typically you never use a ReplicaSet directly, Deployment is all you need. And no, you can't have different Pod templates in one Deployment or ReplicaSet. The point of replication is to create copies of the same thing.
As to how many pods can be run per Deployment, the limits aren't really per Deployment, unless specified. Typically you'd either set the wanted number of replicas in the Deployment or you use the Horizontal Pod Autoscaler with a minimum and a maximum number of Pods. And unless Node limits are smaller, the following limits apply:
https://kubernetes.io/docs/setup/best-practices/cluster-large/