In addition to the usual *AMP stack components -- Apache, PHP, and MySQL -- WampServer includes only maintenance (phpMyAdmin, SQLBuddy) and debugging (XDebug) functions. Perl isn't included. In fact, the WampServer curators don't provide any other components that can be added to the stack. They allow you to add on earlier versions of various stack elements, though. You can, for instance, install older versions back to PHP 4.1.2, or earlier versions of Apache or MySQL. (None of this precludes manually grafting something into the stack, of course.)
Once installed and run, WampServer works in much the same way as XAMPP. It places an icon into the system tray, from which you can start or stop the various services in the stack, jump quickly to key directories (such as the directory that holds the root of the Web server), or open configuration files or logs.
The tray controller also provides quick access to service-specific settings that would otherwise require a lot of poking around under the hood. With Apache, for instance, there's a selectable list of which Apache modules to load and an editable list of alias directories. Changes made to these lists are reflected in httpd.conf, but if you edit httpd.conf directly to make changes, those changes don't show up in the tray controller's list until you restart the whole of WampServer. This doesn't make editing configurations through the tray controller any less handy, but you need to be aware of how changes are kept in synchrony between the tray app and the stack's actual configuration. In short, make configuration changes either in WampServer or in the stack's config files, but not in both at once.
One of the handier options in the tray icon, Put Online/Offline, lets you quickly disable access to the Web stack (the "offline" mode) from anything except the local host. To that end, as a security measure, the admin tools (such as phpMyAdmin) are only available locally by default. On the other hand, the default MySQL password is blank -- a really bad idea.
While most stacks include phpMyAdmin for managing MySQL, WampServer also packages SQL Buddy, a minimal but still immensely functional administrative front end for MySQL. (Be warned that SQL Buddy has some cross-site scripting vulnerabilities in the 1.3.3 edition.) For PHP debugging, there's XDebug, WebGrind, and XDC; note that WebGrind is configured to run only locally for security's sake.