One other notable difference that many people will see is that edX.org as a website has a distinct Course Catalog/Marketing/Corporate site which is very edX specific. That is not made open source, for no other reason - I suppose - than because it is so specific to edX as an organization. Open edX has it's own Course Catalog and Marketing pages inside of it which the community uses and customizes.
As a rough estimate, as an end-user you'll see edX's use of Open edX on the
courses.edx.org and Studio/Insight (for course staff) domains, and the custom marketing site on
www.edx.org and
blog.edx.org.
Other things to note that some features that are in Open edX are turned off on
edx.org. Also many (if not most) of the xBlocks in the ecosystem are not installed/running on
edx.org.
So - in a certain way - Open edX is a superset of features than what is running on
edx.org.
That's a rough approximation. Hope that's helpful.
- Chris