You want to compare data between 2 columns, row-wise.
There is a very simple way to do it.

  1. Select both columns with data
  2. Press F5 and select special (alternatively, from home ribbon, click on Find & Select and then choose Goto Special)
  3. Now, click on row differences and press OK.
  4. Excel instantly highlights all the cells in 2nd column that do not match with first column.
  5. You can simply then change the colour of the font, or apply a fill to the cells, to draw your attention.
You may sometimes also want to highlight all the blank rows in your data, and then delete them in 1 shot.
  1. Select all columns with data
  2. Press F5 and select special (alternatively, from home ribbon, click on Find & Select and then choose Goto Special)
  3. Now, click on blanks and press OK.
  4. Excel instantly highlights all the blank rows.
  5. Simply right-click and click on Delete.