Differences between EJB 3.0 and EJB 2.1

Differences between EJB 3.0 and EJB 2.1

EJB2.0 has Deployment descriptors but in EJB3.0 has no Deployment Descriptors.
EJB2.0 we have to write Home and Remote Interfaces But in EJB3.0 No need to write Home and remote interfaces

Compared to EJB 2.1, EJB 3.0 simplifies the process of creating Enterprise JavaBean applications.

The underlying concept of the EJB 3.0 specification centers on a plain old Java™ object (POJO) programming model that uses Java annotations to capture information that deployment descriptors used to contain

Deployment descriptors are now optional in most cases.

session beans also no longer require EJB-specific component interfaces either.

EJB 3.0 has introduced a lightweight entity bean persistence mechanism through the Java Persistence API. These entities are POJO based and can then be run outside of an EJB container and do not require any interfaces or EJB code in them