Psychology has identified many distinct differences between male and female mental functions Differences in brain structure and function driven by epigenetics and hormones. Women for instance do not fare as well in the field of Mathematics - why is uncertain. There have also been studies that suggest that alarge proportion of women have a hard time comprehending Maps - why is uncertain.
However When it comes to the question of whether there is a significant difference in average I.Q. between males and females - the answer is a definitive NO [ See:
Sex differences on high-range I.Q. tests analysed ]
This is a sloppy graph. I get why they did this - they wanted to illustrate on key point and not muddy the water. The key point is that the male distribution is offset by a few IQ points. What did they leave out? The higher male SD. The male distribution has fatter tails.
The real world indications of those fatter tails are, obviously, male dominance in high IQ professions and tasks and the not so obvious of drastic male failure. More retards, more troubled students. Look at math tests and math classes in public schooling. Girls cluster towards the middle with boys disproportionately on the extremes.
If, as feminist equality apologists claim, the math instruction was biased towards males, then how on Earth could so many young boys being failing and in remedial math compared to the girls.