<!DOCTYPE html>
<html>

<head>
  <style>
    #abs {
      position: absolute;
      left: 0px;
      top: 0px;
      background: silver;
      width: 100px;
      height: 50vh;
    }

    #fixed {
      position: fixed;
      right: 0px;
      top: 0px;
      background: red;
      width: 100px;
      height: 50vh;
    }

    #spacer {
      height: 1000px;
    }
  </style>
<head>

<body>
  <div id="abs"></div>
  <div id="fixed"></div>
  <div id="spacer"></div>
</body>

</html>