Java SE downloads including: Java Development Kit (JDK), Server Java Runtime Environment (Server JRE), and Java Runtime Environment (JRE). JVM – Java Virtual machine(JVM) is a very important part of both JDK and JRE because it is contained or inbuilt in both. JRE is an acronym for Java Runtime Environment. What is JDK? JDK (Java Development Kit) is a software development kit required to develop applications in Java. JDK vs JRE vs JVM · JDK is for development purpose whereas JRE is for running the java programs.