Biological sex is assigned at birth and is based on genitals, chromosomes, and hormones. Gender is what a society says is masculine or feminine.
The reproductive system (sex organs) is used in reproduction and sexual pleasure. It has both external and internal organs. Each part has a medical name and function.
Puberty is a time in life when the body changes and becomes capable of reproduction. Several changes happen to all bodies, but some are specific to males and females.