Whilst the terms 'mental illness', 'mental health' and 'mental disorder' are often used interchangeably, the later two refer to a medically diagnosable range of disorders that result in a significant impairment of a person's thinking, emotional or relationship abilities and which may require treatment and rehabilitation to manage the symptoms.
'Mental Health' on the other hand means emotional and mental well being. It is much more than the absence of mental illness. It is the realisation of a person's potential and the sense of wellbeing that assists people to live fulfilling lives.