Mental illness vs mental condition vs mental disorder I posted this at English.SE, but I'm wondering if you guys can also shine some light here.

Is there perhaps a distinction between mental conditions that are disruptive and mental conditions that just are (and require managing)?

Eg. Someone might argue 'I have depression and this requires curing' (much like cancer requires curing). Someone else might argue 'I have ADHD, and this is just a part of my personality'.

Can someone help shine some light on the distinction between these terms?
To answer those questions, first, we need to define the above-mentioned terms:


  A mental disorder is a syndrome characterized by clinically
  significant disturbance in an individual's cognition, emotion
  regulation, or behavior that reflects a dysfunction in the
  psychological, biological, or developmental processes underlying
  mental functioning (American Psychiatric Association, 2013).  
  
  Mental illness is  characterized as “maladaptive responses to
  stressors from the internal or external environment, evidenced by
  thoughts, feelings, and behaviors that are incongruent with the local
  and cultural norms, and that interfere with the individual’s social,
  occupational, and/or physical functioning (Townsend, 2015). 


Furthermore, no books or reliable sources differently defined medical condition and medical disorder  so, let's assume that these terms are synonymous. 

By definition, medical disorder is any disturbance in a person's mental functioning that can affect his daily routine. Yes, there are medical conditions that are disruptive like patients with psychotic disorders, depressive disorders, substance-related disorders. The latter are considered disruptive in terms that they can harm themselves or others. They require therapies like psychotherapy, pharmacotherapy, etc.
Moreover, there are also medical conditions like personality disorders, human sexuality and gender dysphoria, somatic disorders, etc. that are less likely disruptive but can also affect the person's mental functioning. They can either function well in the society or unable to perform activities of daily living.  

But still, all mental disorders need treatment whether disruptive or not. It is not about how harmful or peaceful the condition is; it is all about the person's mental capacity and functioning without any maladaptive adaptations

Book Source:
 1. Townsend, M. (2015). Psychiatric mental health nursing: concepts of care in evidence-based practice (8th ed.). FA Davis Company: Philadelphia, PA.