Anorexia and Anorexia nervosa: Is there a difference?

Many people refer to anorexia as the popular eating disorder wherein the person afflicted has an irrational fear of gaining weight, resulting to potentially fatal low body weight.
However, what many people don’t know is that this disorder is called anorexia nervosa, not simply anorexia. Anorexia per se is simply the loss of appetite, which can be caused not just by the fear of gaining weight (as seen in anorexia nervosa), but also by several other conditions, such as depression or medication side effects. Most of the time, anorexia is just a symptom of other diseases, like cancer.
Unlike in anorexia nervosa, people with anorexia alone do not necessarily have low body weight. In anorexia nervosa, however, the fear of gaining weight and the poor body image of the person makes her avoid eating, thereby resulting to a critically low body weight.
In other words, anorexia can be treated just by addressing the underlying medical condition that causes it. Anorexia nervosa is a separate disease that involves not just medical treatment, but psychiatric treatment as well.