Namespace vs regular package

Question

What\'s the difference between a namespace Python package (no __init__.py) and a regular Python package (has an __init__.py), especially when

Answer 1

Reading link from Aaron, and PEP420, it appears that the fundamental difference between a namespace package and a regular package, beside the obvious difference that a regular package may contain various initialization code in __init__.py, is that a namespace package is a virtual package whose contents can be distributed in various places along Python's lookup path.

For example, given

a/foo/bar.py
b/foo/baz.py

If both b and a are in Python's path, you can import foo.bar and foo.baz freely.

Of course, this begs the question that, if __init__.py is not needed, then all other things being equal, is it better to make a regular package or a namespace package, but is a little off-topic.