Difference between spring-data-jpa and spring-boot-starter-data-jpa
Check the pom.xml for spring-boot-starter-data-jpa here: https://github.com/spring-projects/spring-boot/blob/master/spring-boot-starters/spring-boot-starter-data-jpa/pom.xml
Read the description tag which says: "Starter for using Spring Data JPA with Hibernate".
So spring-boot-starter-data-jpa uses Spring Data JPA with Hibernate as the implementation. This is hard-coded, so to speak.
If you now check the pom.xml for spring-data-jpa, it is implementation-agnostic. And to use Spring Data JPA in any project, one must provide the implementation to use. Not doing that will give you an error.
Spring Data JPA documentation states that it currently supports Hibernate 5, (Apache) OpenJPA 2.4 and EclipseLink 2.6.1. Read here: https://docs.spring.io/spring-data/jpa/docs/current/reference/html/#new-features.1-10-0
As stated in the docs, the starter
one is a convenient inliner for all required dependencies for this particular library, i.e. includes other dependencies in itself, instead of you writing those manually.
Look into the spring-boot-starter-data-jpa
pom.xml, you will see there it includes spring-data-jpa
as a dependency among many others.
Spring Boot Starters are a set of convenient dependency descriptors that you can include in your application. You get a one-stop-shop for all the Spring and related technology that you need without having to hunt through sample code and copy paste loads of dependency descriptors. For example, if you want to get started using Spring and JPA for database access just include the spring-boot-starter-data-jpa dependency in your project, and you are good to go.