Girls are more "touchy-feely" in general because they are not usually raised up to believe that touching each other and caring about each other is, in some way, bad. As I indicated before, boys are generally taught to not express their feelings, that includes in a touching manner with others, especially with other of the same sex. "Boy just don't do that." It's not that it's some innate thing about boys, it's something taught, something learned from society and parenting.
I'm reminded of watching my son's little "Kindergarten graduation" thingy and the little performances they gave singing songs and such. There were parts where they were supposed to hold hands or link arms with the kid next to them. My son was between a boy and a girl. There was no issue with linking with the girl, but each time he reached out for the boy the other little boy jerked away from him scowling. My son would reach for him each time he was supposed to, only to be refused each time. Obviously, my son has no issue here, the other boy does, and why? Not just because they're boys apparently, because then they'd both have an issue, no...it must have to do with parenting.