XAMPP is a complete web, database and FTP server package for Windows that's ready to go in minutes and completely portable. The full XAMPP package includes:

Apache
MySQL
PHP + PEAR
MiniPerl
OpenSSL
phpMyAdmin
XAMPP Control Panel
Webalizer
Mercury Mail Transport System
FileZilla FTP Server
SQLite
ADODB
Zend Optimizer
XAMPP Security
XAMPP Lite leaves off the additional packages and sticks to Apache, mySQL, phpMyAdmin, SQLite and related packages resulting in an installation that's significantly smaller. There are no upgrade packages for XAMPP Lite like there are for XAMPP, though.