This is the difference between them
Water Footprint
An environmental indicator that measures the total volume of freshwater used to produce goods and services. It is divided into:
Green Footprint: rainwater incorporated into the product or evapotranspired by plants.
Blue Footprint: freshwater consumption.
Gray Footprint: water quality taking into account the pollutants discharged.
LCA Water Footprint
It is based on the Life Cycle Assessment (LCA) methodology, according to ISO 14046. It does not only account for the volume of water consumed, but also assesses the potential environmental impacts related to this expenditure, through various indicators. In other words, it offers an environmental impact approach.