@PersistenceContext
is a specific annotation that declares a dependency on a container-managed entity manager. It allows you to specify more parameters like the persistence type. Setting the persistence type to EXTENDED is important when you want to maintain the persistence context for the whole life cycle of a stateful session bean. @PersistenceContext
is a JPA annotation.
@Inject
is a CDI annotation. It is very generic and can be used to inject a wide variety of objects.