Difference Between Mental Illness and Mental Disorder

Main Difference – Mental Illness vs Mental Disorder

The definition of mental health, as suggested by the World Health Organization, is “a state of well-being where the individual realizes his or her own abilities, can bear up with the normal stresses, occurring in life, able to work productively and efficiently, by a significant contribution to his or her community.” WHO also highlights the fact that mental health “is not just the absence of a mental disorder.” Mental disorder and Mental illness, are two different terms used in psychiatry, which are often confused by many people, since there is no clear-cut demarcation between the two. However, it is valuable to know the difference between mental illness and mental disorder, for the purpose of diagnosis as well as to decide the therapeutic modalities.

Mental Disorder | Definition, Classification

A mental disorder is defined as a change that takes place in an individual’s thinking pattern and emotions which easily interferes with the performance of his day to day activities, mostly due to disturbances taken place in the brain. There are many types of mental disorders, and anxiety and depression are two of them.

An adverse health condition becomes to be known as a ‘disorder’ when it starts impeding one’s daily activities. Similarly, any condition which involves a disturbed brain will also be considered as a disorder, if his ways of thinking and feelings interfere with his normal lifestyle. Psychologists have introduced several concepts to categorize mental disorders depending on various assessments and diagnosis. For example, ICD-10 Chapter V- Mental and Behavioral Disorders, a subdivision of International Classification of Diseases compiled up by the World Health Organization (WHO), and the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) created by American Psychiatric Association (APA) are known to be the universal tools of information and assessment in the fields of psychology and psychiatry.

Main Difference - Mental Illness vs Mental Disorder

Mental Illness | Definition, Classification

The term ‘Mental illness’ is undoubtedly related to the term ‘Mental disorder,’ despite the fact that the former also refers to the form of origin, symptoms, and signs.

It is defined as a pathological condition of the brain, characterized by a set of identifiable symptoms and signs and occurs as a result of various etiological conditions like infections, genetic defects, and environmental factors. For example, some psychiatrists tend to consider Schizophrenia as a mental illness, but not a disorder, because of its strong biological basis of origin.

Difference Between Mental Illness and Mental Disorder

Difference Between Mental Illness and Mental Disorder

Labeling a mental condition as a disorder or illness is quite controversial and tricky since both the terms can be used interchangeably. However, some people suggest the cause of that particular condition to differentiate mental illness and mental disorder.


Mental Illness:  mental illness occurs as a result of an abnormal or disturbed chemicals in the brain, like neurotransmitters.

Mental Disorder: Mental disorders occur due to an abnormality in the normal functioning of the brain.

However, in summary, defining a mental illness over a mental disorder is quite tricky since they are used as general terms for all the conditions which involve abnormalities in the brain, resulting in changes in feelings, emotions, personality and behavior.

Image Courtesy:

“Melancholy” By Andrew Mason (London, UK) – cropped version of:“Melancholys Warm Embrace(CC BY 2.5) via Commons Wikimedia 

“Gautier – Salpetriere” By Armand Gautier – Transferred from en.wikipedia, (Public Domain) via Commons Wikimedia 

About the Author: Embogama

Embogama is a passionate freelance writer for several years. Her areas of interest include general medicine, clinical medicine, health and fitness, Ayurveda medicine, psychology, counseling and piano music