Vegetable and animal fats are similar compounds with different melting points related to the presence of carbon-carbon double bonds (product of the addition of hydrogen to the unsaturated bonds) in the fatty acids components.
Vegetable and animal fats are similar compounds with different melting points. The melting points are related to the presence of carbon-carbon double bonds in the fatty acids components. The addition of hydrogen to the unsaturated bonds (alkenic double C=C bonds) results in saturated C-C bonds, effectively increasing the melting point of the oil and thus "hardening" it. 
