Pretty big difference. An open weight model is a model that you can run on your own machine. You just download and it’s yours to host and use. You don’t need to have anyone host it on their own backend for you, the entire model is available to you to do that on your own. What you don’t have is any control over or access to anything related to how the model was trained. You don’t know what kind of data they used to train it, and how exactly they used that dataset. If you did, that’d be an open source model.

Isn’t that whole “community” mostly just one clearly unwell person?

On Android the default camera app is usually the only app that provides all of that. Which is actually a problem. You usually lose your camera’s higher functions when you install a custom ROM and it’s usually an absolute pain in the ass to get them back if it’s at all possible because cameras and their drivers are all poorly documented proprietary crap.