I'm pretty dense, but who is creating what for whom here? I create a Django app on Arnor then sell it to someone who wants to maintain it? A client logs on to Arnor and requests an app and some developer builds it for them?
Whereas Gondor is for hosting your own code; Arnor is for hosting instances of other people's code. So it's a marketplace for Django developers to sell (or offer for free) out-of-the-box Django projects that people can deploy with a single click, customizing to the extent allowed by the original project creator.