diff b/w jdk and j2sdk?

hi all,
can anybody tell me, that what is the difference b/w jdk and j2sdk?
plz dont tell the full form, plz explain it?

thanks

There's no difference at all. It was originally called the JDK. For a few releases (JDK 1.2 - 1.4) Sun decided to call the JDK (Java Developer's Kit) the J2SDK (Java 2 Software Developer's Kit.) With 1.5, they've gone back to calling it the JDK -- at least sometimes!