Vaporization is a more general term and applies to both evaporation and boiling. Vaporization is any process that describes the conversion of a liquid to a gas.
Evaporation occurs below the boiling point where particles of the liquid go from the surface to the vapor state.
Boiling is a more particular process where a liquid goes to the vapor state at the temperature where the vapor pressure is equal to the ambient pressure. In boiling, vaporization can occur anywhere within the body of the liquid, not just at the surface.
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This statement made by another answerer, "... while boiling occurs at a constant rate for a particular temperature." implies that the rate of boiling will vary with the temperature. That isn't quite true, since the boiling point is a fixed temperature at normal pressure. The rate of vaporization can change, but not as the temperature changes. The rate changes as the quantity of heat transferred changes. The greater the heat, the greater the rate of boiling **at the same temperature**.
