title: How does the official openjdk image differ from ubuntu + openjdk?
body: <p>This is a recommendation from Docker official best practices</p>
  <blockquote>
  <p>Start with an appropriate base image. For instance, if you need a JDK,
  consider basing your image on the official openjdk image, rather than
  starting with a generic ubuntu image and installing openjdk as part of
  the Dockerfile.</p>
  </blockquote>
  <p>But I do not follow how the official openjdk image would be different from ubuntu + openjdk ? Is it because the official openjdk image uses a lighter linux distribution than ubuntu?</p>