What is the difference between ReplicaSet and ReplicationController?

Question

From what I can tell in the documentation, a ReplicaSet is created when running a Deployment. It seems to support some of the same features of a ReplicationController - scale up

Answer 1

Replica Set is the next generation of Replication Controller. Replication controller is kinda imperative, but replica sets try to be as declarative as possible.

1.The main difference between a Replica Set and a Replication Controller right now is the selector support.

+--------------------------------------------------+-----------------------------------------------------+
|                   Replica Set                    |               Replication Controller                |
+--------------------------------------------------+-----------------------------------------------------+
| Replica Set supports the new set-based selector. | Replication Controller only supports equality-based |
| This gives more flexibility. for eg:             | selector. for eg:                                   |
|          environment in (production, qa)         |             environment = production                |
|  This selects all resources with key equal to    | This selects all resources with key equal to        |
|  environment and value equal to production or qa | environment and value equal to production           |
+--------------------------------------------------+-----------------------------------------------------+

2.The second thing is the updating the pods.

+-------------------------------------------------------+-----------------------------------------------+
|                      Replica Set                      |            Replication Controller             |
+-------------------------------------------------------+-----------------------------------------------+
| rollout command is used for updating the replica set. | rolling-update command is used for updating   |
| Even though replica set can be used independently,    | the replication controller. This replaces the |
| it is best used along with deployments which          | specified replication controller with a new   |
| makes them declarative.                               | replication controller by updating one pod    |
|                                                       | at a time to use the new PodTemplate.         |
+-------------------------------------------------------+-----------------------------------------------+

These are the two things that differentiates RS and RC. Deployments with RS is widely used as it is more declarative.