The last is different in that it returns a list, not a tuple. This makes a difference if you want to change the object.

  >>> tuple = x, y = 1, 2
  >>> type(tuple)
  <type 'tuple'>
  >>> tuple
  (1, 2)
  >>> tuple[0] = 1
  Traceback (most recent call last):
    File "<stdin>", line 1, in ?
  TypeError: object doesn't support item assignment
  >>> lst = x, y = [1, 2]
  >>> type(lst)
  <type 'list'>
  >>> lst
  [1, 2]
  >>> lst[0] = 3
  >>> lst
  [3, 2]