Top players rarely run the exact same build, so the sample is grouped by hero tree. A hero tree that at least a quarter of the sample plays, and at least 8 players, gets one build: the one closest to the rest of its group, node for node. The count beside it is the size of that group.

These are Mythic+ builds, what top Discipline Priests ran in keys, and a raid build can differ. Your group and your routes can make another build the better one for you.