JPA is JSR i.e. Java Specification Requirement to implement Object Relational Mapping which has got no specific code for its implementation. It defines certain set of rules for for accessing, persisting and managing the data between Java objects and the relational databaseWith its introduction, EJB was replaced as It was criticized for being heavyweight by the Java developer community. Hibernate is one of the way JPA can be implemented using te guidelines.Hibernate is a high-performance Object/Relational persistence and query service which is licensed under the open source GNU Lesser General Public License (LGPL) .The benefit of this is that you can swap out Hibernate's implementation of JPA for another implementation of the JPA specification. When you use straight Hibernate you are locking into the implementation because other ORMs may use different methods/configurations and annotations, therefore you cannot just switch over to another ORM.

如果没有语言的历史视角和对JCP的理解，有些事情就很难理解。

通常会有第三方开发包来执行官方JDK不包含的功能或填补空白。由于各种原因，该函数可能通过JCP (Java社区进程)成为Java JDK的一部分。

Hibernate(2003年)提供了一种抽象SQL的方法，并允许开发人员更多地从持久化对象(ORM)的角度进行思考。你通知hibernate关于你的Entity对象，它会自动生成持久化它们的策略。Hibernate提供了实现和API，通过XML配置或注释来驱动实现。

现在的基本问题是，您的代码与特定的供应商(Hibernate)紧密耦合，而许多人认为这应该是更通用的。因此需要通用的持久性API。

Meanwhile, the JCP with a lot of input from Hibernate and other ORM tool vendors was developing JSR 220 (Java Specification Request) which resulted in JPA 1.0 (2006) and eventually JSR 317 which is JPA 2.0 (2009). These are specifications of a generic Java Persistence API. The API is provided in the JDK as a set of interfaces so that your classes can depend on the javax.persistence and not worry about the particular vendor that is doing the work of persisting your objects. This is only the API and not the implementation. Hibernate now becomes one of the many vendors that implement the JPA 2.0 specification. You can code toward JPA and pick whatever compliant ORM vendor suits your needs.

在某些情况下，Hibernate可能会提供JPA中没有编码的特性。在这种情况下，您可以选择直接在类中插入Hibernate特定的注释，因为JPA没有提供接口来做这件事。

来源:http://www.reddit.com/r/java/comments/16ovek/understanding_when_to_use_jpa_vs_hibernate/

JPA是规范，Hibernate是遵循规范中规定的规则的实现提供者。

JPA是一个API，由Hibernate实现。Hibernate先于JPA。在JPA之前，您编写本地hibernate代码来执行ORM。JPA只是一个接口，所以现在编写JPA代码并需要找到一个实现。Hibernate恰好是一个实现。

你的选择是这样的: Hibernate, toplink等等…

JPA的优点是它允许您在需要时交换您的实现。缺点是本机hibernate/toplink/等…API可能提供JPA规范不支持的功能。

我尽量用简单的话解释。

假设你需要一辆车，我们都知道他们有几个a级制造商，如梅赛德斯，宝马，奥迪等。

现在在上面的声明中，CAR(是一种规格)，因为每辆车都有共同的特征，比如有四个轮子的东西，可以在道路上行驶。所以它像JPA。 奔驰、宝马、奥迪等只是使用常见的汽车功能，并根据他们的客户基础添加功能，所以他们正在实现汽车规范，如hibernate、iBATIS等。

因此，通过这个通用特性，jpa和hibernate只是一个实现，根据他们的jboss的需要。

还有一件事

JPA包括一些基本属性，所以在未来，如果你想改变hibernate到任何其他实现，你可以很容易地切换，而不需要太多的头痛，这些基本属性包括JPA注释，可以工作于任何实现技术，JPQL查询。

因此，我们主要使用JPA类型技术实现hibernate，只是为了以防万一我们想根据客户需要切换我们的实现，加上您将编写更少的代码，因为JPA中涉及一些常见的特性。 如果有人仍然不清楚，那么你可以评论，因为我是新的堆栈溢出。

谢谢你！

JPA is Java Persistence API. Which Specifies only the specifications for APIs. Means that the set of rules and guidelines for creating the APIs. If says another context, It is set of standards which provides the wrapper for creating those APIs , can be use for accessing entity object from database. JPA is provided by oracle.When we are going to do database access , we definitely needs its implementation. Means JPA specifies only guidelines for implementing APIs. Hibernate is a JPA provider/Vendor who responsible for implementing that APIs. Like Hibernate TopLink and Open JPA is some of examples of JPA API providers. So we uses JPA specified standard APIs through hibernate.