Q5. How would you differentiate JDK, JRE, JVM, and JIT?
A5. There is no better way to get the big picture than a diagram.
JDK, JRE, JVM, and JIT
1) JDK: You can download a copy of the Java Development Kit (JDK) for your operating system like Unix, Windows, etc.
2) JRE: Java Runtime Environment is an implementation of the JVM. The JDK typically includes the Java Runtime Environment (JRE) which contains the virtual machine and other dependencies to run Java applications.
3) JIT: A JIT is a code generator that converts Java byte code into native machine code. Java programs invoked with a JIT generally run much faster than when the byte code is executed by the interpreter. The JIT compiler is a standard tool that is part of the JVM and invoked whenever you use the Java interpreter command. You can disable the JIT compiler using the -Djava.compiler=NONE option to the Java VM. You might want to disable the JIT compiler if you are running the Java VM in remote debug mode, or if you want to see source line numbers instead of the label (Compiled Code) in your Java stack traces.
https://www.java-success.com/why-use-java-and-java-overview-interview-questions-and-answers/