This is a quick workaround if you want to add some content to your Node template (node.tpl.php) that you only want to display on a particular View Mode (such as Teaser or Full View).

It is in fact a simple .php conditional. Let’s say you want content to appear only in the Teaser view mode:

if ($view_mode == 'teaser') {
  // content you want to display
}

For the Full View mode, you just replace teaser with full.

Hope this helps.