It would not make sense to compare apples and oranges. Z-scores allow for comparison of scores, occurring in different data sets, with different means and standard deviations. A z-score indicates the number of standard deviation a score falls above or below the mean. It represents a distribution of standardized scores, called z-scores, as opposed to raw scores (the actual data values). The standardized normal distribution is a type of normal distribution, with a mean of 0 and standard deviation of 1.