While the terms are related, they are not exactly synonymous. Abnormal behavior may simply refer to behavior that deviates from societal norms or expectations, while a mental disorder involves a set of symptoms and criteria defined by the DSM-5 or other diagnostic manuals. Additionally, abnormal behavior can sometimes be adaptive, functional, or even desirable in certain contexts or cultures, whereas mental disorders are typically considered to be harmful or disruptive to individuals' functioning or well-being.