As nouns the difference between ester and lipid

is that ester is a compound most often formed by the condensation of an alcohol and an acid, with elimination of water. It contains the functional group carbon-oxygen double bond joined via carbon to another oxygen atom while lipid is any of a group of organic compounds including the fats, oils, waxes, sterols, and triglycerides. Lipids are characterized by being insoluble in water, and account for most of the fat present in the human body. They are, however, soluble in nonpolar organic solvents.