The difference is not huge, but that is the definition of the median.
Example: There are five kids in the class: Alicia (4’), Beth (4’), Charles (5’), Dan (7’) and Emma (3 miles). The average height of the class is 1060 feet. Are half of the kids taller/shorter than that? Nah. However, the median is Charles’ height, 5 feet. ~Half of the students are above that, and ~half of them are below. If it’s an even number of students, the median is between the two middle ones.
Also, I’m slightly worried about Emma.
As a non-native, I was a bit too old to find the lyrics and get them. After that, it was quite weird to me, but apart from the name being a bit off, I never heard of Gorky Park before.