通俗来说:JDK = JRE +开发/调试工具，其中JDK是我们与Java一起工作的完整包，从创建编译到运行它。另一方面，JRE只是代码(字节码)的运行。

注意:-无论我们是安装JDK还是JRE, JVM都会与这两个包捆绑在一起，JVM是JIT编译器将字节代码转换为机器特定代码的部分。

只需阅读关于JDK、JRE、JVM和JIT的文章即可

JVM

The Java Virtual Machine (JVM) is the virtual machine that runs the Java bytecodes. The JVM doesn't understand Java source code; that's why you need compile your *.java files to obtain *.class files that contain the bytecodes understood by the JVM. It's also the entity that allows Java to be a "portable language" (write once, run anywhere). Indeed, there are specific implementations of the JVM for different systems (Windows, Linux, macOS, see the Wikipedia list), the aim is that with the same bytecodes they all give the same results.

JDK和JRE

要解释JDK和JRE之间的区别，最好是阅读Oracle文档并参考图:

Java Runtime Environment (JRE) The Java Runtime Environment (JRE) provides the libraries, the Java Virtual Machine, and other components to run applets and applications written in the Java programming language. In addition, two key deployment technologies are part of the JRE: Java Plug-in, which enables applets to run in popular browsers; and Java Web Start, which deploys standalone applications over a network. It is also the foundation for the technologies in the Java 2 Platform, Enterprise Edition (J2EE) for enterprise software development and deployment. The JRE does not contain tools and utilities such as compilers or debuggers for developing applets and applications. Java Development Kit (JDK) The JDK is a superset of the JRE, and contains everything that is in the JRE, plus tools such as the compilers and debuggers necessary for developing applets and applications.

注意，Oracle并不是唯一提供jdk的公司。

OpenJDK

OpenJDK是JDK的开源实现，也是Oracle JDK的基础。Oracle JDK和OpenJDK之间几乎没有区别。

区别在这个博客中说明:

Q: What is the difference between the source code found in the OpenJDK repository, and the code you use to build the Oracle JDK? A: It is very close - our build process for Oracle JDK releases builds on OpenJDK 7 by adding just a couple of pieces, like the deployment code, which includes Oracle's implementation of the Java Plugin and Java WebStart, as well as some closed source third party components like a graphics rasterizer, some open source third party components, like Rhino, and a few bits and pieces here and there, like additional documentation or third party fonts. Moving forward, our intent is to open source all pieces of the Oracle JDK except those that we consider commercial features such as JRockit Mission Control (not yet available in Oracle JDK), and replace encumbered third party components with open source alternatives to achieve closer parity between the code bases.

JDK 11的更新

Donald Smith的一篇文章试图消除Oracle JDK和Oracle的OpenJDK之间的差异:https://blogs.oracle.com/java-platform-group/oracle-jdk-releases-for-java-11-and-later

正如@Alan Evangelista在评论中提到的，Java Web Start已被Oracle在Java SE 9中弃用，并在Java SE 11中删除。

JDK:你需要编写和运行java代码的完整包

OpenJDK:一个独立的JDK实现，使它变得更好

JVM:将Java代码转换为字节码，并提供说明如何编译、加载、验证、检查错误和执行Java代码的规范。

JRE: JVM的实现，一些Java库被用来运行程序

JVM is abbreviated as Java Virtual Machine, JVM is the main component of java architecture. JVM is written in C programming language. Java compiler produce the byte code for JVM. JVM reading the byte code verifying the byte code and linking the code with the ibrary. JRE is abbreviated as Java Runtime Environment. it is provide environment at runtime. It is physically exist. It contain JVM + set of libraries(jar) +other files. JDK is abbreviated as Java Development Kit . it is develop java applications. And also Debugging and monitoring java applications . JDK contain JRE +development tools(javac,java)

OpenJDK是sun JDK的开源版本。Oracle JDK是Sun的官方JDK。

JVM Java虚拟机，实际执行Java字节码。 它是JAVA平台上的执行块。它将字节码转换为机器代码。

JRE Java运行时环境，提供了执行Java应用程序的最低要求;它由Java虚拟机(JVM)、核心类和支持文件组成。

JDK Java开发工具包，它拥有开发应用程序软件的所有工具。它是JRE+JVM

Open JDK是Java平台的免费开源实现。

Java虚拟机(JVM)是可以执行Java字节码的虚拟机。它是Java软件平台的代码执行组件。

Java开发工具包(JDK)是Oracle公司针对Java开发人员的产品。自Java引入以来，它一直是迄今为止使用最广泛的Java软件开发工具包(SDK)。

Java运行时环境，也被称为Java运行时、运行时环境

OpenJDK (Open Java Development Kit)是Java编程语言的免费开源实现。这是太阳微系统公司在2006年开始努力的结果。该实现是根据GNU通用公共许可证(GPL)许可的，有一个链接例外。