Youth, adolescence, puberty, pubescence are sometimes used interchangeably to denote the period in life when one passes from childhood to maturity.
Youth is the most general of these terms, being applied sometimes to the whole early part of life from childhood or infancy to maturity. More often, however, youth is applied to the period between the maturing of the sexual organs and the attaining of full maturity. Youth often connotes the freshness, vigor, inexperience, or impetuosity characteristic of the young.
Adolescence designates the same period as youth in the restricted sense, but it carries a stronger connotation of immaturity. Adolescence suggests the awkwardness resulting from the rapid growth during this period and also the mental and emotional instability resulting from the physiological changes. In legal use adolescence designates the period extending from puberty to the attainment of full legal age or majority.
Basically puberty designates the age at which the signs of the maturing of the sexual organs appear (as the beard and changed voice in boys and the development of the breasts in girls); in law this age is commonly fixed at fourteen for boys and twelve for girls. In broader use puberty often designates the period covering the earlier years of adolescence during which the secondary sex characteristics are unfolding.
Pubescence is sometimes used as equivalent to puberty , but often it applies distinctively to the condition of attaining the characteristics (as genital hair) of developing sexuality.