As the name suggests, an adjustment disorder is a psychological presentation in the context of significant stressors. From time to time, we will all have something that we need to adjust to. For instance, children transitioning from kindergarten to primary school, primary school to secondary school etc. For adults, there are transitions from one work environment to another; one relationship to another relationship or no relationship; from being a wife to also becoming a mother etc. While most people may struggle minimally, there are also others who may struggle very hard in the face of identical or similar challenges.
The question is... What is a primary distinguishing difference between an adjustment difficulty and adjustment disorder? In general, the difference lies in the ability of the individual to function as normally as possible. For someone who is experiencing an adjustment difficulty, the individual is still able to function close to normal (e.g., still able to function in school, work, family, home etc). As for someone who experiencing adjustment disorder, this individual may be unable to care for self, unable to perform academically or meet work targets, gets into conflicts regularly or socially withdraws etc. In general, people with adjustment disorder may also present with low mood, anxiety or conduct issues.