What is latent heat of fusion? How does it differ from latent heat of vaporization?

Latent heat of fusion is the amount of heat energy required to change 1 kg of a solid into a liquid at its melting point without any change in temperature. 

Latent heat of vaporization is the amount of heat energy required to change 1 kg of a liquid into a gas at its boiling point without any change in temperature. The key difference is the phase transition involved: solid to liquid for fusion, and liquid to gas for vaporization.