I'm kind of both.
In terms of friends, for a long time my friends have always either been adults or much younger kids. Now, as an adult myself, many of my friends are either teenagers or older adults.
In maturity, a lot of what gets called 'immature' teenage behavior is stuff I've never shown at any age - impulsive risk taking, caring more about my peers' opinions than my parents, wanting to rebel from my parents, etc. So in that sense, I'm unusually mature. I've also been called 'wise' because I think deeply about things and see perspectives other than just my own. I also think about psychology more like a graduate student than an undergraduate student (psychology is my major).
On the other hand, I'm 23 and I still live at home, enjoy playing pretend, have mild separation anxiety and sometimes my 15 year old brother seems more competent at practical living tasks than I am.
But what do you expect from a gifted/disabled person? My skills are all over the place, it's no wonder my apparent 'maturity' is as well.