They measure completely different things. BMI is a pure weight to height ratio--someone could have almost no skeletal muscle and have a "better" BMI than someon

They measure completely different things. BMI is a pure weight to height ratio--someone could have almost no skeletal muscle and have a "better" BMI than someone who works out daily and has heavy muscle density. They're strongly correlated in the statistical sense, but there's still a wide spread of body fat percentage for a given BMI. My guess is that they use different BMI metrics for men vs women when guaging fitness--that's how they keep things gender fair.