Eclipse is a platform you can build your application on and a core Java IDE (effectively a Java source file editor and a Java debugger). MyEclipse is a full-fledged J2EE IDE with the support for JSP, EJB, Servlet, UML, Struts, Hibernate, JSF and other frameworks and technologies. What they have in common is that MyEclipse is built on top of Eclipse so it retains all the functionality that core Eclipse has.