default python spec template: python_sitelib vs python_sitearch

[Roozbeh Pournader]

I'm not sure I really understand the pythong_sitelib and python_sitearch
(from fedora-rpmdevtools' spectemplate-python.spec) macros properly. Two
questions:

1) Will these two macros produce different results on 64-bit machines?
They expand to the same thing on my i386.

2) Should each package use only one of the macros in its %files
section? 

2a) If yes, why don't we make it one macro and define it based on if the
package is noarch or not?

2b) If no, should architecture-dependent files of the package (*.so etc)
use python_sitearch and others (*.py*) use python_sitelib?

roozbeh