Why does steam cause more severe burns than boiling water?

Steam causes more severe burns because it carries extra energy the latent heat of vaporisation.

Both are at 100°C, but when steam contacts skin, it first condenses, releasing 2260 kJ/kg, then cools from 100°C.

Boiling water only releases energy from cooling from 100°C to body temperature.

The extra 2260 kJ/kg from condensation is enormous this is why steam burns are medically more serious.

Steam burns are worse than boiling water burns because steam releases additional latent heat of vaporisation upon condensing.