title: What's the difference between Singleton and Registry design pattern
body: <p>I have some confusion between those two patterns:</p>
  <p><strong>singleton</strong><br />
  Check if the instance exists return it, or create a new one.</p>
  <p><strong>Registry</strong><br />
  Check if the instance exists return it, or create a new one and store it.</p>
  <p>What the difference between them?</p>