Compare/Copy columns from two books?

I've been searching throughout this forum and have found lots of examples but none of them seem to do quite what I want.

I have two wookbooks which are formatted identical and I want to copy a column from each workbook (numeral values) and then in a third column display the difference between the values. Each workbook has 30 sheets and I would like it to go through all 30 sheets copying a particular column from each one and then comparing them and display the difference into a new workbook that contains 30 sheets with each sheet containing the values from both books and the difference. Thanks for your help!