Could smallpox still exist and how does it differ from chickenpox.?

No: The last case of wild smallpox in the world was found in 1977, while 2 lab accident cases were recorded ~1980. Small pox causes dime sized blisters that come up all at the same time and tend to cluster about the face, but can cover the body. Chickenpox blisters come up in waves of 5-10 at a time over a 6 day period and are pellet sized. Spx killed 1/3, cpx killed 1/40000.Stored virus remains.

Smallpox /chickenpox: All naturally occurring smallpox has been eradicated. Incubation is 7 to 17 days for smallpox & 10 to 21 days for chickenpox. With smallpox most lesions are in the same stage of development, are more frequent on face& extremities than trunk & are often on soles & palms. With Chickenpox most lesions are on trunk & not on feet/palms. New lesions come up in succession – so they are in different stage