title: What is the difference between changing package name vs applicationId
body: <p>What is the difference between changing package name vs applicationId to the final apk.</p>
  
  <p>I know it is different for aspect of keeping source code, but lets say I got some app with package name a.b.c.d.
  What will be the difference in the builded apk file</p>
  
  <ol>
  <li>if I rename the a.b.c.d into q.w.e.r and then build the apk file</li>
  </ol>
  
  <p>vs</p>
  
  <ol start="2">
  <li>change the applicationId into gradle with q.w.e.r</li>
  </ol>