As far my knowledge NetBeans is a tool / SW for those who build web applications and for software developers. It is an IDE ( Integrated Development Environment ) which is available as open source software. U can run this program on most operating systems including Windows, Linux, Mac OS X and Solaris. With NetBeans u can develop applications for use via the desktop or on the web. It also develops software for use with mobile devices. The applications can be developed with NetBeans using a variety of coding languages including Java, Ruby (with support for Rails), and C/C++. The feature rich software gives u great options and visual abilities for coding, that allows to not only create the applications but to view them and perform testing to work out all of the kinks and bugs. So Netbeans is not a Programming Language. It helps to save time for coding. In earlier say Java, developer hand written codes in their favourite edit tool and it is bit time consuming.
If u want to design client side code u may use Java Swing and Netbeans helps u to write the codes very easily.
Although NetBeans is certainly an IDE, there is also a NetBeans platform which is a 'reusable framework for simplifying the development of Java Swing desktop applications'.
This is also from Wikipedia:
"The NetBeans IDE bundle for Java SE contains what is needed to start developing NetBeans plugins and NetBeans Platform based applications; no additional SDK is required".
So, although NetBeans is both a platform framework and an IDE, I think you are still comparing two different things (Java and NetBeans).
The NetBeans IDE is written in Java and runs everywhere where a JVM is installed, including Windows, Mac OS, Linux, and Solaris. A JDK is required for Java development functionality, but is not required for development in other programming languages. The NetBeans Platform allows applications to be developed from a set of modular software components called modules. It is a reusable framework for simplifying the development of Java Swing desktop applications (which I told earlier). The NetBeans IDE bundle for Java SE contains what is needed to start developing NetBeans plugins and NetBeans Platform based applications; no additional SDK is required.There is also a good SW called Eclipse, which helps to develop in JAVA.
For more details please link to : http://netbeans.org/project_downloads/usersguide/Using_NetBeans55.pdf