title: Main difference between using define and let in scheme
body: <p>What are the main reasons why someone would use <code>let</code>:</p>
  
  <pre><code>(let((x 4)) (+ x 12))
  </code></pre>
  
  <p>Instead of doing the same thing with a <code>define</code>:</p>
  
  <pre><code>(define x 4)
  (+ x 12)
  </code></pre>
  
  <p>Would there be examples of things that would work with one that wouldn't work with the other approach?</p>