df has 2 stages of power. Their normal use and then their awakenings. So what if the same goes for haki.
Here are my 4 guesses on what they are.
Novice: you can do it but only when stressed out or very mad, people can’t control it or even know they are doing it.
Confidant: you have the basic control over haki you can use it when you want and can use it whenever.
Advanced: this is where you start developing special skills.
With observation it’s future sight and with armourment it is the ability to shoot out a burst of energy at close range.
Master: this is when you reach the absolute limit and start pulling off abilities that are out of this world.
For observation it is the voice of all things where you can talk and control all things.
With armourmemt I think it’s invincibility.
When brook stabbed big mom he couldn’t even crack the skin, when luffy hit Kaido he couldn’t even hurt him.
With conquorer I don’t know but maybe it’s god ability. The power to control the weather or something.