title: Compare dataframes in scala and write the mismatching old and new columns to new dataframe
body: <p>I have two df's  </p>
  
  <p>df1<br>
  ID |BTH_DT    |CDC_FLAG|CDC_TS                       |CNSM_ID<br>
  123|1986-10-07|I       |2018-10-10 05:51:24.000000941|301634310<br>
  124|1973-02-15|I       |2018-10-10 17:12:22.000000254|298910234</p>
  
  <p>df2<br>
  ID |BTH_DT    |CDC_FLAG|CDC_TS                       |CNSM_ID<br>
  123|1986-10-07|I       |2018-10-10 05:51:24.000000941|\c<br>
  124|1973-02-15|I       |2018-10-10 17:12:22.000000254|298910234</p>
  
  <p>How do i compare two df's and write the mismatching columns alone to different df?</p>
  
  <p>ID |CNSM_ID<br>
  123|301634310<br>
  123| \\c</p>
  
  <pre><code>df2.except(df1)  
  </code></pre>
  
  <p>above isn't serving the purpose</p>