title: Difference between SDL_Scancode and SDL_Keycode
body: <p>I am in a learning process of SDL library by version 2.0.
  When I checked out SDL_Event handling , I got two different representations for keyboard event.</p>
  <blockquote>
  <p><strong>SDL_Scancode</strong></p>
  <p><strong>SDL_Keycode</strong></p>
  </blockquote>
  <p>I could not understand the difference between them.Despite trying.</p>
  <p><strong>What are those differences ?</strong> and <strong>Why are those as amount two ?</strong></p>