Entity beans represent data in a domain model. Entity beans are persistent. They live as long as the data lives in the domain model. Entity beans can survive EJB server crashes. Any EJB server crash is always transparent to the client.
Entity beans have a persistent object reference.
The object reference encapsulates the persistent key for this bean. Session Beans A session bean is created by a client and, in most cases, exists only for the duration of a single session. It performs operations on behalf of the client, such as database access or number crunching based on some formula. Although session beans can be transactional, they are not recoverable following a system crash. They can be stateless or they can maintain conversational state across methods and transactions.