Curiosamente, las cadenas de documentación para los dos no son totalmente iguales en Python 2.5.1:
>>> import string
>>> help(string.split)
Help on function split in module string:
split(s, sep=None, maxsplit=-1)
split(s [,sep [,maxsplit]]) -> list of strings
Return a list of the words in the string s, using sep as the
delimiter string. If maxsplit is given, splits at no more than
maxsplit places (resulting in at most maxsplit+1 words). If sep
is not specified or is None, any whitespace string is a separator.
(split and splitfields are synonymous)
>>> help("".split)
Help on built-in function split:
split(...)
S.split([sep [,maxsplit]]) -> list of strings
Return a list of the words in the string S, using sep as the
delimiter string. If maxsplit is given, at most maxsplit
splits are done. If sep is not specified or is None, any
whitespace string is a separator.
de excavación más profunda, se verá que las dos formas son completamente equivalentes, como se llama en realidad string.split(s)s.split() (buscar dividir -funciones).
He reemplazado 'str' por 'text' debido a 'str' es un nombre incorporado en Python (tipo ('') == str). – jfs