title: What is difference among styles.xml and themes.xml
body: <p>May I know what is the difference between <code>styles.xml</code> and <code>themes.xml</code>? To me, they just look same as both XML are in the same format.</p>
  
  <pre><code>&lt;style name="...
      &lt;item name="...
  </code></pre>
  
  <p>So, in my app which provide customization coloring, size, drawable, ... do I need both <code>styles.xml</code> and <code>themes.xml</code> as well? How should I decide which XML to put in which file?</p>