The mean is one kind of descriptive statistic, it is calculated by adding up all of the individual scores and dividing by the total number of scores
The median is a second kind of descriptive statistic, it is calculated by arranging the data scores from lowest to highest. The median of the data set will be the middle score, if 2 numbers are the middle number then the median is half way between these two scores e.g 6 and 7 are the middle scores, the median in this case would be 6.5