JPA stands for Java Persistence API, which is a specification for persisting, reading, and managing data from Java objects to relational tables in a database. Spring Data JPA is a library or framework that adds an extra layer of abstraction on top of JPA providers like Hibernate. It aims to significantly reduce the amount of boilerplate code required to implement a data access layer for various persistence stores.

Spring Data JPA makes it easy to implement JPA-based repositories. It provides sophisticated support to build repositories based on Spring and JPA, support for Querydsl predicates and thus type-safe JPA queries, transparent auditing of domain class, pagination support, dynamic query execution, ability to integrate custom data access code, and validation of @Query annotated queries at bootstrap time.

In summary, JPA is a specification for persisting data between Java objects and relational databases, while Spring Data JPA is a library or framework that provides an extra layer of abstraction on top of JPA providers like Hibernate, making it easier to implement JPA-based repositories and reducing the amount of boilerplate code required to implement a data access layer for various persistence stores.