Why are there four IDEs: NetBeans, Sun Studio, JSE, and JSC?
There’s a blog entry on this topic, but the short answer is: The IDEs that Sun delivers as products serve multiple audiences and serve different functions. For instance, Java Studio Enterprise provides some extra enterprise-class tools for service-based application development and modeling facilities using UML. Java Studio Creator is designed for the rapid development of Java applications by those either new to Java or domain experts who needed an easy way to leverage the power and portability of Java without enduring the steep learning curve needed by other IDEs (more thoughts on this here) . And Sun Studio provides features needed for C/C++ development on Solaris and Linux.