There were many factors determining the strength of a person in the Sun Moon Realm, but they generally fell into three categories.
Taking the same realm as an example, these factors were: the cultivation state of the inner source space, the inherent strength of the divine abilities, and the profundity of the cultivation method.
Any significant disparity in any of these aspects could lead to a huge difference in power. If two or more aspects were lacking, even within the same realm, one might be overwhelmed.
Besides these three aspects, another significant factor was the power of mysterious treasures.
A person in the early stages of the Sun Moon Realm wielding a top-grade mysterious treasure would naturally have exceptional combat power.
However, using a mysterious treasure far beyond one's realm could present a prominent issue: the inability to perfectly control the power.
Often, this problem was minor and could even be ignored.