What's the main difference between Java SE and Java EE?

Java SE (formerly J2SE) is the basic Java environment. In Java SE, you make all the "standards" programs with Java, using the API described here. You only need a JVM to use Java SE.

Java EE (formerly J2EE) is the enterprise edition of Java. With it, you make websites, Java Beans, and more powerful server applications. Besides the JVM, you need an application server Java EE-compatible, like Glassfish, JBoss, and others.

Java SE refers to the standard version of Java and its libraries. Java EE refers to the Enterprise edition of Java which is used to deploy web applications.

Java EE is enterprise edition.

Includes jsp, servlets, beans, and some other stuff for server programming.

Java SE is standard edition. This is plain old Java. Includes GUI stuff.

First, J2SE and J2EE have been renamed. They're now Java SE and Java EE.

Essentially, Java SE is your standard Java designed for end-users. That's what you'd develop to for desktop applications. Java EE is the enterprise edition, designed for server programming, such as SOA and web applications.

The biggest difference are the enterprise services (hence the ee) such as an application server supporting EJBs etc.