Why Java installs JRE when installing JDK

Question

When I install the Oracle JDK, it also installs a separate JRE. For example:

JDK:

C:\Program Files\Java\jdk1.7.0_40

JRE:

C:\Program Files\Java\jre7

Isn't JRE a subset of JDK? Why do I need JRE and libs executables twice?

In particular, there is a difference between java.exein JRE/binand that in JDK/bin?

I believe adding JDK / bin to the path should be sufficient.

I am on Win 7 (in case this is relevant).

Answer 1

JDK , jre Java (, , , ) . .

, , , jre

Answer 2

Java Runtime Environment (JRE) JVM, Java-. , JVM.

Java Development Kit (JDK) JRE. , .

, JDK JRE.

.