Thanks for sharing @nickmilo – that mini taxonomy of higher-level notes is something I’ve been looking for.
Maybe one thing that is resulting in people talking past each other is the distinction between mechanism vs. policy.
For e.g., “Zettlekasten” is a set of specific note-taking/organization and workflow mechanisms to implement a specific policy (philosophy/ approach/ etc.) of note taking and thinking. Concepts from this framework can be generalized or used in other frameworks, either by abstracting the mechanism or policy or both. For e.g, the “atomic note” can be seen purely as a mechanism (allowing for fine-resolution linking) or policy (“your notes should capture single concepts in your own words etc. etc.”) or both.
In much the same way, there are general mechanisms for introducing higher-level order/structure or even “adjacent-level” order/structure for the notes. A note with links to other notes is one very general mechanism of doing it. So are tags, folders, dataview queries, etc. Given the different purposes and uses and needs for this higher-level order, we might identify specific policies and guidelines that describe how and why we use these mechanisms.
Maybe we can think of the “MOC” as a general mechanism (extending the “note of links” with specific structure and meaning), and all the other note types (hub, index, structure, etc.) as various “mechanism+policy” implementations with usages and purposes to help organize?
A related issues is, of course, terminology. There namespace is crowded, there is no real controlled vocabulary or even the possibility of coming with one. Terms are oversubscribed or redundant or otherwise have no real definition in some cases or distinction in others. But that’s the stuff of internet arguments 
(Incidentally, the Lua programming languages emphasizes providing “mechanisms not policy” as a fundamental aspect of its philosophy, which is where I learned this concept from, and have since found it very useful in teasing apart aspects of complex higher-order systems such as this. https://www.lua.org/doc/cacm2018.pdf )