Mental illness is due to chemical malfunction in the brain and can be cured or reduced with medicines. But , mental retardation can be reduced only by vocational and behavioral therapy.
People with mental illness can work in the mainstream after treatment. But, people with mental retardation can only do jobs that match their ability.
NGOs working with mentally ill people, demand that mentally ill and mentally retarded must be under the same category and/or premises. But, mentally ill people may turn violent and mentally retarded people who are child-like cannot defend themselves. So, the debate continues.