How is a specification different from an API?

Question

API

Understanding Hibernate. It turned out that JPA is a specification, and Hibernate is an ORM that implements it, and Hibernate can work through its own API, and not just through the JPA API.

How is a specification different from regular interfaces/APIs? After all, the specification, as far as I understand, also declares what must be implemented, as well as in the interface contract.

Answer 1

In this case, it differs in that it is a standard specification. A Hibernate developer can change his API anytime and anywhere, but JPA changes only in the process of many years of coordination by about fifty large companies.

Answer 2

JPA - Java Persistence API
Your question is how is API different from API.
The answer is nothing.