Perhaps the best way to answer this is to think about an adolescent as a 4th or 5th grader (with a clear fact that this is a general group of students). They are likely to play with some toys at one time while being more serious with friends at other times.
I would tend to refer to adolescents as those in the pre-puberty classification.
For young males the movement to puberty is physically the scenario. Along with physical body changes comes clear emotional ups and downs. These young people are likely to be 5-8 graders- middle school students.
While I am not an expert, as an educator this is the general way we look at the difference.