I totally agree with the comments above. Mental disorder is more specific things among the psychological condition of an individual. Mental health is a result of the general situation of the person.
Mental health is over all state of one's emotional and mental well-being. Whereas mental illness is the condition that affects behaviour and thoughts of one.
you explained this so well :)
That's a good question and one I think people tend to use interchangeably.
But mental health I think refers to the general and overall psychological health of an individual whether good or bad. There isn't a distinction of either the well-being or lack thereof in this term.
Mental Illness though is the absence of psychological wellbeing. Although the patient themselves might not necessarily acknowledge the lack of well-being, it will be plain to see.