I’d classify a beginner as someone who has read something in the press or another projects and winds up here. They might be highly technical or not at all. They want to know about the concepts and ideas and how to interact with what’s there so far (ie the Databrowser). They want to know timelines, next steps, what they can do to help, and crucially where to look for more information. So everything at a high level. In your example of setting up a server, a graphical stepthrough would belong in Beginners, whereas more detailed information about interfaces, frameworks, APIs, developer tools etc would go into Developer.
Ultimately there are no hard and fast rules and quite a lot of playing by ear. If everything landed up in beginners it would make sense to split it into different categories (or add sub categories) to keep it useful to genuine beginners / new arrivals. It’s easy for Mods to move threads and posts from one category to another if they don’t really fit.