Link the tables together by ID#
Use a layout based on 2012 table
Add a field for 2013::ID# onto your layout based on 2012
Do a find on that field...either "=" (blank) for those missing, or "*" (something) for duplicates.
To find those missing use an omit request with the * operator. This is one case where the lone = operator doesn't work. To create an omit request, click the Omit button in the status area tool bar.