Hibernate SessionFactory vs Service Registry

Question

Before sleep mode 4

The way to implement a session connection is with SessionFactory only.

Example:

Configuration cfg=new Configuration();
Configuration cfg=cfg.configure("mysql.cfg.xml");
SessionFactory sf=cfg1.buildSessionFactory();

Hibernate 4.0.4.1.4.2

It changes with the ServiceRegistry concept, and the implementation method with ServiceRegistry and SessionFactory.

Example:

 Configuration configuration = new Configuration();
 configuration.configure();

 serviceRegistry = new ServiceRegistryBuilder().applySettings(
            configuration.getProperties()).build();
 sessionFactory = configuration.buildSessionFactory(serviceRegistry);
 return sessionFactory;

Hibernate 4.3

ServiceRegistryBuilder () is also deprecated and replaced by the standard ServiceRegistryBuilder ().

Example:

serviceRegistry = new StandardServiceRegistryBuilder().applySettings(
                configuration.getProperties()).build();

My questions:

• What is the difference between b / w SessionFactory and ServiceRegistry?
• Why is the concept of ServiceRegistry required?
• What is the advantage of deploying ServiceRegistry on top of SessionFactory?
• What is the difference between b / w ServiceRegistryBuilder () and StandardServiceRegistryBuilder ()?