Compared to women, men invariably have more muscle mass and less body fat than women. Women require more body fat for procreation and breast feeding offspring.
Men are stronger than women. In terms of lower body strength, a woman is only 75% as strong as a man. In terms of upper body strength, a woman is only about 55% as strong as a man. Men's greater strength translate to better performance in sports. For example, "greater strength drives difference in power between sexes in the conventional deadlift exercise."
Sex differences in gray matter in the brain anatomy causes cognitive, emotional, and behavioral differences between men and women. In fact, "sex can be reliably predicted by brain structure when considering the brain mosaic as a whole."
There are sex-associated behavioral differences in mating, parenting and aggression. These behaviors have historically been essential for survival and propagation. Sexual aggression is no longer needed to ensure continuation of the species, but nonetheless persists.
There are significant differences between men and women in terms of sexual interest and activity. For instance, men have a higher sex drive, think about sex more often, report more frequent sex fantasies and more frequent feelings of sexual desire. Moreover, heterosexual women and lesbians share more commonalities while heterosexual men and gay men share more commonalities.