A stage of being mature and behaving differently from others is what I understand by the word maturity.
Maturity can also be define as a stage in our life where we begin to develop our body, like the girls they will start having body shapes and for the men their voice will be big and bears will be growing in their body especially their faces, this can be considered as a sign of maturity in human body.

A different approach to maturity. Not a lot of users have talked about this perspective but I think it's a very important aspect of maturity. When a child reaches puberty, not only his/her body changes but there are constant changes to his nervous system as well.

Age has no business to do with experience although, sometimes the people we grow with as our age mates gives us life experience

100% agreed on this. I've given similar perspective in my post regarding the connection of age and maturity. It's the experience that shapes us. A person could be 80 years old but caged up in a place wouldn't be as mature as a person who has seen it all.

It was wonderful reading your post, keep shining.