1. J2SE is the Java 2 Standard Edition that contains your basic core Java classes. This is the one that most people use to write your standard applets and applications. 2. J2EE is the Java 2 Enterprise Edition and it contains classes that go above and beyond J2SE. In fact, you will need J2SE in order to use many of the classes in J2EE. Some of the things that J2EE provides are server-side classes such as Servlets and EJB's. It also contains Security API, Java Mail API, XML Parsers etc., Java Messaging Service API, and a few others. A few of these API's have been included in the new J2SE 1.4 version and are now considered standard. The XML API is an example of this. 3. J2ME is for developers that code to portable devices, such as a palm pilot or a cellular phone. Code on these devices needs to be small in size and take less memory. So you will want to use J2ME if you code for a PDA.
J2EE 企业版本，大型服务器程序
J2ME 手机版本，手机程序以后有问题，先看看百度，实在解决不了再来这里，你这种问题就是在浪费版面，百度上有更多详细的解说
J2EE就是JAVA 2 Enterprise Edition
J2ME就是JAVA 2 Micro Edition