Z-score is a statistical tool that is used to determine the probability of finding a number or a value under a normal distribution plot. A normal distribution assumes that the mean is equal to zero and that the standard deviation is equal to 1. Using the z-score table, we can find the probability either on the right side or the left side.
The statement above is false as the z-scores depend on their locations in the distribution and differs in every way. This would result to erroneous computations. So the correct way to determine the difference of probabilities is to get the individual probabilities and get the difference thereafter.