Do We Have This One?

In Real Life hair rarely shows how mature you are. In fiction, hair length is an easy way to tell a persons experience.

You'll see a male teenager or kid with long hair, or maybe an afro even. A few years down the line, maybe a child later, and he'll be clean cut.

Likewise for girls.

Between Intergenerational Friendship's, or maybe even relatives or friends with a few years difference, the older one will often have short hair and the youngest a longer length.

In older fiction, with girls at least, this was quite often Inverted. Short hair was a sign of immaturity, sometimes a Tomboy too, while long hair was more mature and feminine.