What is the difference between SQLITE3 and Python 2.5, Pysqlite and APSW?

>>> from pysqlite2 import test
Traceback (most recent call last):
 File "", line 1, in 
 File "pysqlite2\test\__init__.py", line 35, in 
 from pysqlite2.test import dbapi, types, userfunctions, factory, transactions,\
 File "pysqlite2\test\dbapi.py", line 27, in 
 import pysqlite2.dbapi2 as sqlite
 File "pysqlite2\dbapi2.py", line 27, in 
 from pysqlite2._sqlite import *
ImportError: No module named _sqlite

I want to know What is the difference between python2.5, pysqlite and apsw’s sqlite3?
When I try to install pysqlite on windows vista using python2.5, I have a bumpy run, please refer to the following:

>from http://sqlite.org/ download.html download sqlite and unzip them to windows/system32 folder and put sqlite3.dll into c:/python25/Lib folder
>download pysqlite windows installer
>try to run the following in python shell When:

>>> from pysqlite2 import test
Traceback (most recent call last):
 File "", line 1, in 
 File "pysqlite2\test\__init__.py", line 35, in 
 from pysqlite2.test import dbapi, types, userfunctions, factory, transactions,\
 File "pysqlite2\test\dbapi.py", line 27, in 
 import pysqlite2.dbapi2 as sqlite
 File "pysqlite2\dbapi2.py", line 27, in 
 from pysqlite2._sqlite import *
ImportError: No module named _sqlite

I would like to know any experience with the above three types of sqlite binding to python can comment on their advantages and disadvantages such as performance
I want to know if it is worth trying pysqlite or apsw

thank you

pysqlite is the same as sqlite3 (the windows binary built into python 2.5 In package)