The Medical Model:
This is the model that views disability as being an impairment in an individual, in a manner where the person is sick or ill and is in need of treatment. Expansion of this model leads to the conclusion that a disabled life is not worth living, because it is full of disease, and it is only by getting "better" or "cured" that gives worth. This also puts the burden of disability on the person, who is then expected to "defeat" or "overcome" their disability in order to be a valued member of society. Because of the goal to "cure" the disease of disability, the medical model gives doctors and professionals authority over people's bodies.
The Social Model:
It's a model on disability that separates the terms impairment and disability. Under it, disability is the inaccessibility and barriers in a society that limits and excludes people with impairments. Impairments are characteristics, features, or attributes of a person that are long term, may or may not be the result of disease or injury, and 1) affects a person's appearance and/or 2) affects the functioning of a person's mind or body, either because or regardless of society, and/or 3) causes pain, fatigue, affect communication and/or reduces consciousness.
I try not to use the word "impair", because to me it doesn't sound much different than how the medical model defines disability. However, the social model of disability is the model I use in combination with Neurodiversity.
Medical model thinking is enshrined in the liberal term "people with disabilities," and in approaches that seek to count the numbers of people with impairment, or to reduce the complex problems of disabled people to issues of medical prevention, cure or rehabilitation. Social model thinking mandates barrier removal, anti-discrimination legislation, independent living and other responses to social oppression (Shakespeare 268).
The philosophy and movement of thought that typical human neurology includes a wider range of neurological types than previously thought. Each neurological type has its own diverse scope of strengths, weaknesses and challenges. However, due to the idealizations, values and structures of a society, these neurological types are impairments and disabilities, and so are considered abnormal. The aim of the Neurodiversity movement is to raise awareness to these issues, and erase the barriers that disable neurologically diverse people.
The short forms for neurologically typical, this term was created as a sort of tongue-in-cheek jab at the medical profession and all the labeling that occurs around people with neurological differences. It's often used more seriously now, to refer to non-autistic people. However, it should be noted that as the philosophy of neurodiversity is embraced more and more, that neurotypical will become a dated term that will fall out of use, or else expand to include various forms of neurology as being typical.
Shakespeare, Tom. "The Social Model of Disability". The Disability Studies Reader. 3rd ed. Ed. Lennard J. Davis. New York: Routledge, 2010. 266-73. Print.