Well, there are differences between men and women and also differences between how men and women interact together, both between men and other men, and women and other women, and between men and women. There's unwritten social "rules" in regards to male to male affection, even a hug is generally reserved for family members or very close friends, and even then, the contact in a man to man hug has its own unwritten rules, IE no caressing with the hands, don't linger for more than 2s, keep waists apart so you know what's don't touch, etc etc. Even if unaware of the social rules involved, most men subconsciously obey them. There's certainly just limited intimacy between men, and most heterosexual men, really don't desire any more intimacy than that with other men.
as to why women are more comfortable with higher intimacy between themselves? I have no idea, that's a mystery to me.
hugs between a man and woman, even as platonic friends, will have different body language, now if there's no interest beyond that platonic friendship(or they're family) there probably won't be any caressing and there may be back patting instead (whereas between 2 men it's basically a given that they slap each other's backs if they hug), but it's more likely to be a tighter hug, and linger a bit longer. It's just less awkward and rigid feeling, less like you're both subconsciously following a rulebook to not give anyone watching the wrong idea.
Even if it's a woman who is totally off limits IE married right in front of her husband, or a woman who is definitely "not in a million years" 0 interest at all even if she threw herself at you.. it's still more comfortable and less awkward than hugging male friends.. maybe your father and your brothers .. that's about the only exceptions, and even then, that's debatable. Being that my father's dead and was out of my life by the time I was in school... and I have no brothers I can't really say for sure.
I mean, I don't even hug my uncles, but my aunts want me to hug them when saying goodbye after a visit, and sure, I'm fine with that.
It's just different, even without any possibility of sexual activity the interactions and affection are different.
as to why women are more comfortable with higher intimacy between themselves? I have no idea, that's a mystery to me
Yeah I have noticed that.
in case you're baffled at the idea that there's actual man hug etiquette...