Chickenpox
A self limiting viral illness. Incubation period 14-21 days. Spread by droplets from mouth and nose or from blister fluid. Causes brief flu like illness then a rash. The spots are red and elliptical in shape. They develop into blisters which soon burst. They then become scabs. The itching is helped by calamine lotion. Calpol or Junifen are useful for fever or pain. The child can return to school when the blisters have all dried up.
Shingles
This is caused by reactivation of an earlier ( decades perhaps) chickenpox infection. It causes a painful blistering rash sometimes around the eye but usually in a band around one side of the chest or abdomen. The pain may precede the rash. For most people no treatment is needed beyond painkillers. If frail, elderly or unwell with AIDS, leukaemia or cancer then drug treatment is needed.
You can catch chickenpox from people with chickenpox or shingles. You can only get shingles if you have had an earlier bout of chickenpox.