Puberty is the process of physical changes by which adolescents reach sexual maturity, i.e. become capable of reproduction. Puberty refers to the bodily changes, while adolescence is the period of psychological and social transition between childhood and adulthood.
In non-specialized discussion and writing, the meanings tend to get blurred, and puberty can be used to refer to the period during which the changes happen, getting a meaning closer to adolescence. Adolescence still encompasses a typically larger period of time, however: puberty is over when the young individual's body has fully transformed, while it takes some more time for him or her to be recognized as an adult. Criteria for the latter are somewhat arbitrary, the typical example being “having reached the age of majority or being emancipated” (the age of majority depending on the country of residence). Some people even talk of 20-something adolescents to refer to people who have not yet reached an autonomous state of living, while being of full legal age.