Java Terms Explained

I started learning java and I thought it would be a good idea to help the user community of this wonderful language from a beginner's perspective.
http://java.sun.com/developer/onlineTraining/new2java/programming/learn/unravelingjava.html

What is the difference between SDK and JDK.
Java 2 SDK is by popular user opinion has been reverted back to JDK where JDK stands for J2SE Development Kit. J2RE has been reverted to JRE.
http://java.sun.com/javase/namechange.html

Another thing to note is that there is no difference between 1.5.0 and 5.0 version. The leading 1. was dropped and the new 5.0 numbering format has been adopted by Sun. The latest release of Java is version 6.0 and instead of referring it by J2SE 6.0, Sun prefers to call the new version Java SE 6.0. They have dropped the 2 altogether.
http://java.sun.com/j2se/versioning_naming.html

I would blame the Sun Marketing people of confusing people with the versioning. I hope the above links would help simplify things for the beginner.