def intersection(list1, list2):
  """
  Returns the intersection and then the items in list2 that are not in list 1.
  """
  
  int_dict = {}
  not_int_dict = {}
  list1_dict = {}
  for e in list1: list1_dict[e] = 1
  for e in list2:
    if e in list1_dict: int_dict[e] = 1
    else: not_int_dict[e] = 1
  return [list(int_dict.keys()), list(not_int_dict.keys())]