Apache is a free and open-source cross-platform web server software.
Debian is a Linux software which is a free open-source software.
Mod_perl is an optional module for the Apache HTTP server. It embeds a Perl interpreter into the Apache server. In addition to allowing Apache modules to be written in the Perl programming language, it allows the Apache web server to be dynamically configured by Perl programs.
Mod_python is an Apache HTTP Server module that integrates the Python programming language with the server. It is intended to provide a Python language binding for the Apache HTTP Server.
Perl is a family of two high-level, general-purpose, interpreted, dynamic programming languages.
Python is an interpreted and general-purpose programming language.