- SE (standard edition) which includes all the basic classes that you would need to write single user applications.
- EE (Enterprise Edition) is set up for multi-tiered enterprise applications, or possible distributed applications. If you'd be using app servers, like tomcat or websphere, you'd want to use the J2EE, with the extra classes for n-tier support
- J(2)EE, strictly speaking, is a set of APIs which enable a programmer to build distributed, transactional systems. The idea was to abstract away the complicated distributed, transactional bits (which would be implemented by a Container such as WebSphere,JBoss or Weblogic), leaving the programmer to develop business logic free from worries about storage mechanisms and synchronization.
- J(2)EE is actually a collection of technologies and APIs for the Java platform designed to support "Enterprise" Applications which can generally be classed as large-scale, distributed, transactional and highly-available applications designed to support mission-critical business requirements.
The specifications (defined by Sun) describe services, application programming interfaces (APIs), and protocols.
The 13 core technologies that make up J(2)EE are: JDBC, JNDI, EJBs, RMI, JSP, Java servlets, XML, JMS, Java IDL, JTS, JTA, JavaMail, and JAF.
The J(2)EE product provider is typically an application-server, web-server, or database-system vendor who provides classes that implement the interfaces defined in the specifications. These vendors compete on implementations of the J(2)EE specifications.
J(2)EE includes EJB, Web Apps ( servlest and JSP ), transactions, webservices, management, and application servers.
In many situations the enterprise applications needs to connect to with a number of legacy systems, they are not only "web pages", and with the features availalble on the "edition" of java that kind of connectivity can be solved.
