Difference between Serializable and non Serializable object save into database
In general, no difference at all. having an entity as Serializable for persistence is not a must, and strictly depends on the framework which you are using for your persistence layer.
e.g. Hibernate does not require at all, though it is a best practice to make entities Serializable, as per JPA specification -
If an entity instance is to be passed by value as a detached object (e.g., through a remote interface), the entity class must implement the Serializable interface.
So if you need detached entity for example in HTTP session, or to pass to another layer, Serialize them, etc - you need to have your entities as Serializableobjects.