GNU/Linux Lubuntu 18.04 Installing Java Guide
How to Install Oracle Java SE on Lubuntu 18.04 Bionic LTS GNU/Linux.
And the Oracle Java SE Lubuntu Bionic Release includes:
- Java Runtime Environment to Run Java Software
- Java Development Kit to Develop Java Software
Moreover, the Java OpenJDK (Open Java Development Kit) is the Free and Open Source Implementation of the Java Platform, Standard Edition (Java SE).
Where the Oracle JRE/JDK is based on the OpenJDK Source Code. In Addition, it contains Closed-Source Components.

GNU/Linux Lubuntu 18.04 Java SE Installation Guide