dict.items()和之间有适用的区别dict.iteritems()吗？

从Python文档中：

dict.items()：返回字典的（键，值）对列表的副本。

dict.iteritems()：在字典的（键，值）对上返回迭代器。

如果我运行下面的代码，每个似乎都返回对同一对象的引用。我缺少任何细微的差异吗？

#!/usr/bin/python

d={1:'one',2:'two',3:'three'}
print 'd.items():'
for k,v in d.items():
   if d[k] is v: print '\tthey are the same object' 
   else: print '\tthey are different'

print 'd.iteritems():'   
for k,v in d.iteritems():
   if d[k] is v: print '\tthey are the same object' 
   else: print '\tthey are different'   

输出：

d.items():
    they are the same object
    they are the same object
    they are the same object
d.iteritems():
    they are the same object
    they are the same object
    they are the same object