Who was greater in their individual sport, Michael Jordan or Wayne Gretzky (and why)?

Michael Jordan and Wayne Gretzky were both extremely successful in their sports. It is difficult to compare athletes across sports because the skills needed for each sport are so different. Michael Jordan certainly had more fame and influence on the culture of the United States compared to Wayne Gretzky.

I would not say that means that Michael Jordan was a better at playing basketball than Wayne Gretzky was at playing hockey, but it does mean that Michael Jordan's legacy is greater.