title: Change the color of cells in one column when they don't match cells in another column
body: <p>I want to check if the values in one column are the same as values in another column. Whenever the values are not the same, I would like to change the color of these cells.</p>
  
  <p>For example:</p>
  
  <p><img src="https://i.stack.imgur.com/IycFA.png" alt="http://i60.tinypic.com/2ai203l.png"></p>
  
  <p>Column I, Column AA
  both have the value of a the first month in years from 1318 till 1500 "Arabic Calender"
  but I want to check which of these values doesn't match and color them with yellow for example.</p>
  
  <p>In this case, both cells in row 3 should have a different color after the checking operation.</p>
  
  <p>Is there a way to do this?</p>