title: python pandas : compare two columns for equality and result in third dataframe
body: <p>how to print the result in the separate dataframe after comparing it with two columns in different dataframes.</p>
  
  <p>consider two dataframes:</p>
  
  <pre><code>df1 = pd.DataFrame({'col1':['audi','cars']})  
  df2 = pd.DataFrame({'col2':['audi','bike']})
  
  print (df1)
  
      col1
  0  audi
  1  cars 
  
  print (df2)
  
       col2
  0   audi
  1   bike
  </code></pre>
  
  <p>now the result should be in a different dataframe.</p>
  
  <pre><code>      col1  col2  result
  0     audi  audi   no change
  1     cars  bike   changed
  </code></pre>