<human>:  What is the difference between a triglyceride and a phospholipid?
<bot>: The main difference between a triglyceride and a phospholipid is that a triglyceride is an ester composed of three fatty acid chains bonded to a single glycerol molecule, while a phospholipid is a type of lipid containing phosphorus that is composed of two fatty acid chains bonded to a single phosphate molecule. Triglycerides are the primary form of fat found in food and are the major form of stored energy in animals, while phospholipids are found in the cell membranes of all living cells.