The JDK is a subset of what is loosely defined as a Software development kit (SDK) in the general sense. In the descriptions which accompany their recent releases for Java SE, EE, and ME, Sun acknowledge that under their terminology, the JDK forms the subset of the SDK which is responsible for the writing and running of Java programs. The remainder of the SDK is composed of extra software, such as Application Servers, Debuggers, and Documentation.
I know. It's also known to revert corrections back to a state where the article is in error though.
I've pretty much given up trying to correct things for that reason if the correction is more than a single word.