The Difference Between the Best and Worst Coaches in the NBA

Anthony Fowler says there's a 14 point difference between the best and worst coaches in the NBA. How narrow of a band are we looking at when we're trying to compare impact that a specific coach has on a team? Is it 14 wins or 14 points? I have no clue. What I would love to know is what it looks like in practice. But even that is an apples to apples because interaction between a player and the coach as a constant is a totally different thing.