The latter has the following diagnostic criteria in DSM V:
One or more symptoms of altered voluntary motor or sensory function.
Clinical findings can provide evidence of incompatibility between the symptom and recognized neurological or medical conditions.
Another medical or mental disorder does not better explain the symptom or deficit.
The symptom or deficit results in clinically significant distress or impairment in social, occupational, or other vital areas of functioning or warrants medical evaluation.
If you have been diagnosed with this I suggest you seek a second opinion.
Unfortunately there is a long and shameful history of certain doctors ignoring the physical aspects of me/cfs and trying to class it as psychosomatic or a conversion disorder.
Multiple sclerosis used to have the same problem and was seen as "hysterical paralysis".