This sounds easy but it is no quite. If you search through the Internet then you might get some links but some of the methods is not as particular. Like this http://support.microsoft.com/kb/213367 one. The MATCH might be fine but it does not explain much and the Macro … Marco?? Who want to write Macro if there is a function to compare the 2 columns?
The practical and easy way I found is this one http://www.youtube.com/watch?v=ciQeNOv7u5I the key function is
Watch the video and see the explanation.