What are the main differences between StatefulSet and Deployment objects in Kubernetes?

The main differences between StatefulSet and Deployment in Kubernetes are related to state management and pod identity:

• Deployment is designed for managing stateless applications. Pods created through Deployment are interchangeable and do not have persistent identifiers. When updating or scaling, new pods are created without preserving the state of old ones.

• StatefulSet is used for applications that require maintaining state and the uniqueness of each pod. Each pod receives a stable network identity and persistent storage (PersistentVolume), which is important for databases, clusters, and other stateful services.

Key points:

Characteristic	Deployment	StatefulSet
Pod identity	No unique identifiers	Each pod has a unique name
Data storage	Usually stateless	Support for persistent volumes
Startup order	Pods start in parallel	Pods start and are deleted in order
Updates	Rolling update without order	Updates with order control

Thus, if an application requires maintaining state and pod uniqueness, StatefulSet is chosen; for stateless applications, Deployment is used.