i dont know about that, all the guys i know are as emotionally mature as girls, in the past there was a big difference because boys were taught to repress their feelings " a man doesnt cry" etc.
Physically there is a difference on average, yes but it cant be more than about a year, and sexually males mature faster than girls by about 20 years.
In terms of personality, i feel that males are significantly more mature than females. It seems to be that females are targeted by stereotypes and bombarded with advertising and crap which they are easily influenced by. Males tend to grow into 'themselves' or become their true self waaaaay before girls.
Maybe thats because of the other stereotype "real men dont care what other people think" hence males aspiring to be a real man wont conform to society but will be an individual and like his own tastes no matter what other people think.
Reminds me of mean girls " So.... do you like anyone?" " umm well theres this one guy in my maths class..." "ooooh no! no no no, you cant like him! thats reginas ex!"
Girls gossip, go on about useless crap like shoes and when they get serious talk about emotional stuff like their boyfriend cheating on them. men talk trash, tell jokes and when we get serious talk about world events and politics.