Module vs. Package?

x may be a package or a module and y is something inside that module/package.

A module is a .py file, a package is a folder with an __init__.py file. When you import a package as a module, the contents of __init__.py module are imported.

A Python module is simply a Python source file, which can expose classes, functions and global variables.

When imported from another Python source file, the file name is treated as a namespace.

A Python package is simply a directory of Python module(s).

For example, imagine the following directory tree in /usr/lib/python/site-packages:

mypackage/__init__.py <-- this is what tells Python to treat this directory as a package
mypackage/mymodule.py

So then you would do:

import mypackage.mymodule

or

from mypackage.mymodule import myclass