2) Java has a separate installation for development because it is a compiled language . You need a compiler and some supporting files and classes (that is, the JDK) to develop software. But you don’t need that to run Java programs, you just need the Java Runtime Environment.
Read moreDo you need a JDK for Java?
Typically, if you are only interested in running Java programs on your machine or browser, you only need to install JRE. However, if you would like to develop an application and do Java programming, you will need JDK .
Read more