The cry-out of “Java != JavaScript” is not a new expression. I learned it in year 2001 when I started learning JavaScript.
But as “Java2Script” project, it links “Java” and “JavaScript” together by a Java to JavaScript compiler. It is unavoidable to explain these two languages in Java2Script manner before making senses.
“Java” is a word for “OO” (Object Oriented) concept in the eyes of Java2Script. C++ is considered not a pure OO language, but C# may be. And there are other OO languages. But the well-known one should be Java. Java2Script just takes Java as a great OOAD tool (language tool) to analyze, design and implement desktop applications or rich client platform (RCP).
Naming ECMAScript as JavaScript is big mistakes for early Netscape developer. But we already accepted it. Even though lots of JavaScript syntaxes are similar to Java, it does not matter that JavaScript is a different language. And ActionScript, which is used in Flash, is another script language which is based on ECMAScript. It seems that few cares about comparison between Java and ActionScript. Whatever language is, Java2Script developers need tools to design rich internet applications (RIA).
On fields of language conversion, you may already know that GWT is also a Java to JavaScript compiler that links together these two languages. And I also know that there are other languages to JavaScript compilers. For example, C# to JavaScript compiler ( http://jsc.sourceforge.net/ ), and Java to ActionScript ( http://osflash.org/j2as )
… // more needs to to be explained
In some simple words, “Java” and “JavaScript” is not two languages but two tools (or tool sets) in the opinions of Java2Script. By Java2Script compiler, we can use these two tools to develop once but get both RCP and RIA at the same time. That is the key advantage of Java2Script.
We do not care what languages are used. We know we use OO concepts to design things and get what we want by using the existed tools.