I wonder what your requirements are to say how lucid you were. When do you find your dream was high lucid? when low?
For me, it has to do with how aware I am of my situation. In a low lucid I tend to go along with the dreamscenario. Eg when I became lucid during an exam, I filled in nonsense answers because I was dreaming. In a high lucid, I am very aware that I’m inside an illusion of my dream, for example by playing with the boundaries of the dream and seeing what is behind my dream and such experiments.
I always make an effort to move away from the dream plot.
Low for me is when the lucidity is more fragile and could easily wane - but could also become high using commands/rubbing hands and remembering it is a dream.
High level are just stable LDs. If I ever get super aware, I would need to use another description. Master level LD would do it.
I have never really thought of levels much, but reading this I realised that I do consider my LDs in low / high levels. For me they are based on how conscious I am of it being a dream. Or basically, how lucid I feel?
It’s hard to explain, but I mostly rate it when I am awake. If it feels like I was completely aware in the dream then it is a high level. If it feels like I was only slightly aware / not fully in control, then it was a low level. Basically, I think.
I rank mine by how long they were; short, medium, or long. Then by how much awareness, vividity, and control I have in the dream.
Awareness being; how much of myself am I in this dream and can I think clearly.
Vividity being; how many senses do I have, are the senses dull or sharp.
Control being; how much of want I want to do can be done.
I got this from reading another dreamer’s journal on this forum, but I can’t remember their name… So sorry for stealing their idea! But it’s been a great help
I think for me the main way I differentiate is based on whether or not I’m capable of stopping to think.
In a low-level LD, I tend to act on impulse. Even though I know I’m dreaming, my thoughts are very hazy, sort of like right when I wake up actually. Because of this, I tend to just take the first actions that come to mind—whatever seems fun or interesting in the moment. As a result it’s easy for me to lose lucidity or wake up in a low-level LD, because I’m unlikely to take the time to try to stabilize the dream or strengthen my lucidity.
In a high-level LD, I’m aware enough to be able to step back and take a moment to consider what actions really make sense for me to take. This kind of “bigger picture” awareness means that I can take time to try to recall my address, rub my hands together, touch the ground, etc., or more carefully pick a goal or activity based on what I’m really interested in instead of just what’s suggested by the scene or my raw gut impulses.
The difference seems to be mainly one of executive function, I guess, which makes me wonder about the neurology of lucid dreaming. I wonder if there are certain parts of the brain that switch to a more awake-like kind of activity in a high-level LD, but stay in a more NLD-like configuration in a low-level LD.
didn;t we have this topic already? 
Because of this, I tend to just take the first actions that come to mind—whatever seems fun or interesting in the moment. As a result it’s easy for me to lose lucidity or wake up in a low-level LD, because I’m unlikely to take the time to try to stabilize the dream or strengthen my lucidity.