PHP in templates is so last decade
Packages are complete Textpattern installations for specific purposes and/or markets.
A Package would start off with a branch of Textpattern, throw a Theme on it, add some Plugins, and make the necessary configuration settings, like adding sections.
Who makes these packages?
Well you pick:.
We assemble them:
The Package is shipped with source code, database, and accompanying documentation.
Note: Packages are not forks, think of meta-packages in Debian.