persistence.xml used to define the
JDBC driver and connectivtey with database additional that you define the
unit name.
orm.xml you can skipped it and use the annotation insted of that.
orm.xml used to mapping object to database.
best regards,
Best Regards,
Moayad Abu Jaber
SCJP 5.0, SCWCD 1.4, SCBCD 5.0