Ok, then there should be zero difference between realized masters.
There is zero difference in the substance of their realization.
Okay, then they should all be in perfect agreement in their teachings.
Not at all. There is no difference in the realization of masters because what is realized is the nature of mind. This is the same for everyone everywhere.
There is endless variation in the expression of that realization because it is, as Malcolm has said often, a personal experience. I will add that this realization is expressed or manifest differently for everyone because individuals vary tremendously.
I will also add that the difference bewteen and master and an ordinary practitioner is that a master has not just glimpsed the nature of mind but is exceptionally at ease there, can access it at any time, can introduce others to it because he/she basically dwells there, can teach others "about" it and so on.
When you have a dzogchen teacher, you have a relationship with someone who can not only introduce you to the nature of your mind but someone who can guide you to the full expression of that in your daily life. HOW that occurs varies from master to master.
I say this because I have such a teacher. My circumstances are different from his and different from my fellow practioners. He is a master because he understands the nuances of this and he (unlike me and my fellow practitioners) is clear about this in all circumstances.
Dzogchen is always lived in the context of an individual life.
My apologies to oldbob for spouting off like this <laughing> but somebody had to do it.