The biggest personality difference between high school and college graduates is probably their level of maturity. At the end of high school, many students still carry over childish traits from their younger years -- getting upset over minor problems, failing to follow through on initiatives and avoiding responsibility. However, after college graduation, many of these traits disappear or are minimized. The graduate has learned that he will not get far in the professional world if the traits are carried along with him there.
Many college graduates find that they have developed an increase in their own self-awareness over the course of four years. They have a better understanding as to their social and career interests, motivations and stress tolerance thresholds. They may even work this understanding into a career that benefits from such knowledge, such as becoming a therapist. Other times, it helps them have better relationships with their peers, family members, or future co-workers.
Many college graduates also develop more social aspects of their personalities now that they are mostly in the company of their peers, as opposed to a world of adults. Shy, withdrawn high school students may become social butterflies in college since they no longer have to fear what parents will think of their various associations. Likewise, more outgoing teenagers may turn into young adults who value introspection. This can occur due to the more mature nature of the tasks and subjects they are asked to handle, which can often involve a great deal of profound thinking.
Finally, many students graduate college with a greater sense of social awareness and a sincere desire to promote positive change in the world. This can occur because many current events are discussed in campus classes or in clubs and activities that aim to further certain causes. The college graduate completes her education with a greater sense of social empathy and responsibility.