<p>I understand the difference between ReplicaSet and ReplicationController, of former being Set based and the latter Equality based. What I want to know is why was a newer implementation (Read ReplicaSet) introduced when the older ReplicationController achieves the same functionality.</p>

<p><code>ReplicaSet</code> is usually not standalone, these are owned by <code>Deployment</code>. A single <code>Deployment</code> can have many <code>ReplicaSet</code>s in its life cycle as new <code>Version</code> deployment added one more <code>ReplicaSet</code>. </p>

<p><code>Deployment</code> allows us to rollback to previous stable releases if required.</p>
