Girls generally tend to grow mentally and physically faster than what the boys grow with. It has been seen over ages how girls of smaller age group often tend to be smart, intelligent and active more as compared to boys. Girls have always been seen as multi-taskers. Girls are generally seen to have more stable emotional balance as compared to boys. They respond to critic situations more calmly and level-headed as compared to the boys.
However, exceptions exist.
The hormone responsible here is basically puberty. Biologically, it hits different people at different time. But, studies show that girls tend to hit their puberty at an early age.
I hope this answer helps!😊