Off topic:Compare gene files within two folders

Question

[priyag8179]

I have two folders "Old_2014" and "New_2015" both folder has files such as

Old_2014=abl_results 
         abc_results
New_2015=abl_results
         abcd_results

I need to find the files which are there in the old but not in the new and at the end the, the results file need to have the unique value