First of all i suggest not to use MSI installers provided on the Downloads page. They have a lot of bugs. It is better to generate your own MSI. If you install Spark with JRE it will use this bundled JRE and there wil be no conflicts. This bundled JRE is in C:\Program Files\Spark\jre\. You can always delete it (while Spark is not running) or install without it and Spark will automatically switch to the JRE installed on a computer. Online means it doesnt have JRE bundled. Offline is provided with the bundled JRE.