My son and I were talking about the word: "overachiever". He had an understanding that it meant that an individual overachieves in relation to the established standard in his cohort. I said no, that an individual overachieves when he overreaches what is expected of him because of hard work. I won.
Overachievers are individuals who "perform better or achieve more success than expected." The implicit presumption is that the "overachiever" is achieving superior results through excessive effort.