Being a general-purpose language, Perl has a lot of advantages, including many functions that are capable doing nearly everything. It has modules that enables it to be downloaded and loaded in a Perl script. Processes of the scripts can also be made via the web server or by a user from the shell, if needed.
Using PHP also has plenty of advantages. As it is included in HTML pages, it means that all your work can be done in the same directory, and that a single file can contain HTML and PHP code. This greatly improves tasks like dynamic page processing. Hence, it makes work done more efficiently.
Perl scripts need to be loaded separately from HTML pages as they are kept in a special directory, which makes management more difficult. PHP integrates itself very well in HTML files if the server is configured to parse PHP files. Therefore, scripts don't need to be loaded from a separate location. PHP files also need to be parsed by the server at each load, so they should not be used in files that don't need to be processed.
You do not need Smarty to edit PHP scripts, and being new to the language, I would recommend staying away from Smarty until you understand PHP.
