Compare two worksheets and insert row

I have an excel 2010 workbook with a worksheet that pulls in data from an outside source (about 150 cost codes and descriptions).  On another worksheet in the same workbook I have data in the first two columns that was copied from the first sheet originally.  When a new query is run to update the first sheet, I would like to include code that would compare the two sheets row by row and update the second sheet by inserting rows if a new cost code is found.  

Please let me know if you need more information.
Thanks