How to distinguish ReplicaSet, Deployment, StatefulSet, and DaemonSet by functionality and application in Kubernetes?

In Kubernetes, ReplicaSet, Deployment, StatefulSet, and DaemonSet are different controllers that manage pods but have different purposes and features:

• ReplicaSet — ensures a specified number of identical pods. If a pod crashes, the ReplicaSet will create a new one to maintain the desired count. It is usually not used directly but managed through Deployment.

• Deployment — a higher-level abstraction over ReplicaSet. It allows managing application updates (rollouts, rollbacks), scaling, and versioning. Deployment creates and manages ReplicaSets.

• StatefulSet — manages pods with persistent state. Each pod gets a unique, stable identifier and persistent storage. It is used for applications where startup order, stable network identities, and data persistence are important (e.g., databases).

• DaemonSet — ensures that a copy of a pod runs on each (or selected) node in the cluster. It is used for running system agents, monitoring, logging, and other tasks that need to run on all nodes.

In brief:

• ReplicaSet — maintaining a number of identical pods.
• Deployment — managing the lifecycle of ReplicaSets and updates.
• StatefulSet — managing stateful pods with unique identifiers.
• DaemonSet — running pods on all cluster nodes.