The standard J2SE contains classes that form the core of the Java language. Such as database connection, interface definition, input/output and network programming.
Enterprise J2EE includes J2SE courses as well as developing enterprise applications. For example: EJB, servlet, JSP, XML, transaction control.
Miniature J2ME contains some classes of J2SE, which is used for software development of consumer electronic products. For example: pager, smart card, mobile phone, PDA, set-top box.
Simply put:
J2se java 2 Simple Edition for Small Programs
J2ee java 2 Enterprise Edition for Large Programs
Mobile phone version J2me java 2 mini version.
Their scope is: J2SE is included in J2EE, J2ME includes the core classes of J2SE, but some new proprietary classes are added.
In addition, it also includes some third-party sdk, such as Android SDK for developing Android applications and so on.