Depression can manifest as fatigue, but fatigue does not equal ME/CFS or even CFS. Fatigue is a symptom of many illnesses. ME/CFS is a complex multisystem disorder including autonomic and immune dysfunction among a number of other problems. Depression is NOT a symptom of ME/CFS. Some people with ME/CFS have reactive depression after having their lives destroyed by this horrific illness, but that's true of most people with severe chronic illness.