I found a planet with rings similar to your 4th picture (and I assume the next couple are different angles of the same one?). If yours is anything like mine it was considered a single ring even though there is a huge gap between them. I tested that by flying through the gap several times. I figured if it wasn't truly a gap and just sparsely populated then the game would force me to drop from SC but it did not do that and I was able to fly through the gap without issue. Maybe I'll post a picture of mine when I get home. I love finding interesting rings!
I think whether they are one ring or not depends on whether they maintain the same orbital velocity, separate rings will be vastly different. I have seen a ring with many gaps you can fly straight through, and a week or so ago I got pulled out of SC by a ring I couldn't even see, so results vary.
Interesting, I had not thought of that being the way to classify separate rings! I had never thought about it much though to be completely honest. There's always something new to learn about this game!
here is the one I found:
View attachment 148825
EDIT: Looking back through screenshots, I have so many pictures of cool rings that I wish I would have payed closer attention to... I am too quick to take a picture and move on without really thinking about how these things actually work. I need to change that about myself.