<P> The most obvious differences between males and females include all the features related to reproductive role , notably the endocrine ( hormonal ) systems and their physiological and behavioral effects , including gonadal differentiation , internal and external genital and breast differentiation , and differentiation of muscle mass , height , and hair distribution . There are also differences in the structure of specific areas of the brain . For example , on average , the SDN ( INAH3 in humans ) has been repeatedly found to be considerably larger in males than in females . </P>
which body system differentiates a male from a female
endocrine ( hormonal ) systems and their physiological and behavioral effects , including gonadal differentiation , internal and external genital and breast differentiation , and differentiation of muscle mass , height , and hair distribution