What is the difference between a Java API and a library?

Question

I know that an API is called a set of functions used to call something, and a library is a collection of classes, but what is actually API in package like java.lang

Answer 1

Api is a list of all classes that are part of the JDK .it all includes all Java Packages,classes and interface ,along with their method,field, and constructor.

A java package is a technique for organizing java classes into namespace similar to the modules of Modular,provide modular programming in java packages can be in compresses files called JAR files,allowing classes to be downloaded fast as groups rather than individually.