I have personally had FND for nearly a year now (FND diagnosed in Feb 2015) and I personally think there are major differences between FND and CD even though the symptoms are indeed very similar.
Definition of Conversion Disorder / CD:
Conversion disorder / CD is a diagnostic category used in some psychiatric classification systems. It is sometimes applied to patients who present with neurological symptoms, such as numbness, blindness, paralysis, or fits, which are not consistent with a well-established organic cause, and which cause significant distress. It is thought that these symptoms arise in response to stressful situations affecting a patient's mental health. Conversion disorder is considered a psychiatric disorder.
Now having that in mind lets look at the definition of Functional Neurological Disorder / FND:
Functional Neurological Disorder / FND is a neurological disorder for which very little is currently known. It is an umbrella term for a variety of symptoms which look similar to those caused by neurological conditions such as Multiple Sclerosis (MS) or Parkinson's Disease, including weakness, fatigue and seizures. It is currently believed that Functional Neurological Disorder arises from a problem with the patient's Central Nervous System, which is not sending and receiving signals correctly. The brain of a patient with Functional Neurological Disorder is structurally normal, but functions incorrectly.
Currently, traditional tests and investigations such as blood tests, MRI and CT scans will show no abnormalities in patients with FND; however, it has been discovered that there is a difference in blood flow to certain key areas of the brain when scanned using Functional Magnetic Resonance Imaging (fMRI). Although currently there is no way to 'see' whether a patient has FND, their symptoms are real, and often cause disability and distress to the individual.
Now you have read both definitions of FND & CV heres my conclusion to Functional Neurological Disorder vs Conversion Disorder.
Conversion Disorder / CV, is "a psychoanalytic concept that describes the occurrence of motor or sensory neurological symptoms, are not explained by disease, not malingered but are thought to relate to psychological factors"
Functional Neurological Disorder / FND is a problem that comes from a sufferers nervous system that controls the movements of your entire body, causing abnormal functions in the brain sending the wrong signals to the body. Causing the unknown symptoms but with no psychological stressor.