Familiarity means knowing and utilizing.
But what can be done is limited.
Beyond a certain scope, it's basically useless.
However, mastery is completely different. With a mere thought, mountains and rivers can be restored.
Moreover, it's not constrained by various rules. You can accomplish more as long as you desire.
Upon reaching the Immortal Realm, one begins to familiarize oneself with the various powers of rules of this world.
The Undying Immortal can make the physical body imperishable.
It's equivalent to delving into the essence of life.
The Grotto Heaven Immortal comprehends the spatial essence of this world, capable of creating small spaces and traversing the Outer Cosmic.
The Creation Immortal starts familiarizing with creation rules. In summary, with each step forward, one gains a deeper understanding of the essence of this world, hence being called an immortal.
An immortal achieves what others cannot, possessing mythical methods.
