from filecmp import dircmp

def diff_files(dcmp):
   for name in dcmp.diff_files:
      print "diff_file %s found in %s and %s" % (name, dcmp.left, dcmp.right)
      # copy file to backup dir here
      for sub_dcmp in dcmp.subdirs.values():
         print_diff_files(sub_dcmp)

dcmp = dircmp('dir1', 'dir2')
diff_files(dcmp)