What are the differences between entity beans
which are in the EJB 2.0
specification and entity classes
which in the 3.0
spec
In EJB 2, entity was a bean meaning that it had to live in a container and need to be managed (similar to other beans, say stateful, stateless, message driven beans).
However in EBJ 3.x, entity is a POJO class - meaning that it can live outside container also.. plain java application can make use of entities as ORM layer with any providers supporting it..