title: Difference between styles.xml (res\values\styles.xml) and styles.xml (res\values-v21\styles.xml)?
body: <p>What is the main difference between these two files : styles.xml (res\values\styles.xml) and styles.xml (res\values-v21\styles.xml ?</p>
  
  <p>For targeting old android versions, which file should we modify?</p>