Water content is determined by the Karl Fisher titration method & it consists of only water i.e., moisture content. The results do not contain other volatile matter except the water.
The Loss on Drying test is designed to measure the amount to water & volatile matters in a sample when the sample is dried under specified condn's. e.g. 105°C, 3hrs.
Loss on drying (LOD) is determined by heating the sample below its melting pt in an oven & it includes all volatile matter including water content & solvents. Loss on drying is an approx analytical method removing not only water but all other volatile impurities like alcohol, etc.. from the sample.