title: what is difference between 'SCRIPT_FILENAME' and 'REQUEST_FILENAME' on RewriteModule?
body: <p>what is difference between <code>SCRIPT_FILENAME</code> and <code>REQUEST_FILENAME</code> in mod_rewrite ?</p>
  
  <pre><code>RewriteCond %{SCRIPT_FILENAME} -f
  RewriteCond %{SCRIPT_FILENAME} -d
  </code></pre>
  
  <p>and</p>
  
  <pre><code>RewriteCond %{REQUEST_FILENAME} -f
  RewriteCond %{REQEUST_FILENAME}
  </code></pre>