Alrity, sorry for the late response. Needed a permission from some people to use pics of their fish.
Firstly, I need to make clear that whatever I say in this post is my own perspective on what constitutes a ranchu or a lionhead, and probably will only serve to confuse you more

For me, if we live in the western world (or any other place other than Japan), it pays to stick to the TVR (Top View Ranchu) and SVR (Side View Ranchu) rule. Why? Because in Japan, there is no TVR and SVR classification, every ranchu is called just
ranchu and is judged by a standard. Which standard is it? It's the standard we in other places other than Japan called the
TVR standard and the fish is judged predominantly from the top. Other than Japan, we usually put our fish in an aquarium and judge them from the side, hence the need for the SVR standard. So to apply Japanese ranchu (TVR) standard to our aquarium side-viewed fish is a step in the wrong direction, IMO.
Now, about the classification of Lionchu and Ranchu (again, this is my own understanding). To answer this, we need to understand the various types of wen.
There are a few types of wen in goldfish, but I'll list the 2 main types of wen occuring in ranchus & lionheads:
1. Lionhead wenThis wen, the way I describe it, is full of little bubbles that covers the ENTIRE head generously, evenly, and somewhat loosely that when the fish swims, u can see the bubbles jiggle freely on the head. When viewed from the top it looks rounded. This type of wen usually occurs in Lionheads (of course), Thai black SVRs, and Chinese-bred SVRs (if u go to goldfishnet.com's auction, u can always see a few examples of Chinese-bred ranchus)
Examples:

Pics from chinagoldfish.comAs you can see in the first pic, the entire head is covered evenly in bubbles (and loosely, too). U can easily imagine it jiggles around when the fish swims.
2. Tigerhead wenThis, in my opinion, is the ideal ranchu wen. This wen is compact, doesn't jiggle, and has clear distinctions between the wens in different parts of the face. The cheeks are very prominent. The forehead is not high but still bumpy. I like the way some sources say that the forehead should resemble the Chinese character "王" (wáng) which means king/ruler, or in my words the forehead should resemble a bodybuilder's "six-pack". Usually occurs in Japanese TVR and Thai SVR.
Example:
Pic from chinagoldfish.comSo to me:
Ranchu --> Any dorsal-less, short-tailed goldfish that has a curvy enough backbone and a wen (any kind)
Lionchu --> Any ranchu that has Lionhead-type wen.
Lionhead --> Any dorsal-less, short-tailed goldfish that has a straight backbone and a wen (any kind)
Personally, I don't really care if it's a ranchu or a lionchu, as long as the wen is not too overly big and heavy that it hinders the movement of the fish. Balance is paramount for me.
Then, what is the perfect SVR for me?

Pics courtesy of Mr. HermantoThe two fish above are self-bred by Mr. Hermanto, a hobbyist from Indonesia.
Both ranchus, IMO, are almost perfect examples of SVR.
The first one could have a slimmer stomach, but it has perfect curved backbone, perfect tail, compact wen, and perfect posture.
The second one's tail could've been set a little higher and more upright, but once again perfect backbone, wen and posture. Moreover it's only a year old and already 18+ cm (7+ inches) long.
On daryl's own self-bred ranchu.
Both are nice fish, but the backbone's arching too high for my liking and the angle drop to the tail is not acute enough. The stomach looks to be a bit flat and needs to be more rounded. The head is set quite low so instead of looking proud and perky, it looks droopy and resigned. Here's an outline of what improvements I can see in one of ur fish:

Once again, I'd like to remind you all that all I wrote above is from my own perspective and most hobbyists will have their own unique views of lionchu, ranchu, lionhead, TVR, SVR, etc etc etc. Mine is based from what I've so far read, seen, and study about ranchu in general, compound them together into what I see as sensible and easy way to classify and look for good standard in ranchu.
I'd really like to hear more opinions about this matter (I'm sure daryl also)