Going to the Materia Medica, we read about each remedy and see that Arsenicum patients tend to be chilly and restless and thirsty for sips of water. They also do not usually have the intensity one usually finds in the patient requiring Belladonna. The level of fear is less intense (more of an anxiety and less terror or panic).

Also the Belladonna patient tends to be thirstless rather than thirsty and tends more to a constipation than to a diarrhea.

There is one other remedy that came to my mind while creating this sample. It was Nux-Vomica. The Nux patient also tends to be chilly, averse to company, has stomach upsets and is very sensitive to being touched. I was curious as to why Nux did not  seem to show up in the top ten or so remedies in the chart

 I looked further and found that the thirst and the vomiting DURING diarrhea, both of which are very strong symptoms in the case, are NOT usual Nux-vomica symptoms and that is why it was far down on the list. This also demonstrates that each time we look at a remedy we can learn another aspect of that remedy.