Question

What is the difference or relationship between str and string?

import string 
print str
print string 

Answer 1

str is a built-in function (actually a class) which converts its argument to a string. string is a module which provides common string operations.

>>> str
<class 'str'>
>>> str(42)
'42'
>>> import string
>>> string
<module 'string' from '/usr/lib/python3.1/string.py'>
>>> string.digits
'0123456789'

Put another way, str objects are a textual representation of some object o, often created by calling str(o). These objects have certain methods defined on them. The module string provides additional functions and constants that are useful when working with strings.