What is the difference between smallpox and chickenpox?

There’s quite a bit of difference. Smallpox is a very virulent disease that has been practically eliminated by the smallpox vaccine — that little scar on your left arm is your smallpox vaccination. Prior to the prevalence of vaccination, smallpox was a killer disease. Now, one rarely hears about it since all babies are vaccinated before they are six months old. Chicken pox is a common childhood disease, characterized by the appearance of small, red blisters that itch intensely. If the child scratches them or tries to pick the scab, they can leave permanent scars. Chicken pox is very contagious. During the incubation period, the time before the lesions appear, the child is likely to feel sick and have a high fever. There is no vaccine for chicken pox that I know of, but once a child contracts it, there is lifelong immunity. Some related illnesses, caused by similar viruses are cold sores and herpes.

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They’re caused by different viruses.