Pubic hair grows. Eggs in the ovaries start to mature each month. Menstruation, also called a period, begins. In boys, among other changes, the voice deepens, the testicles and penis get bigger and the testicles begin to make semen and sperm. Ejaculation can be achieved.
Pubic hair grows, as do whiskers.
Adolescence is a broader term bringing in not only biological maturation, but also social, psychological and cultural maturation. It is the passage from dependent child to independent adult. Unless children turn into adults, they will not be able to fulfill that mission. Modern-day twists on puberty, however, have made it more difficult for all parties concerned. In part because of better nutrition, puberty begins earlier on average than in generations ago.