Lipids can contain two monomers: fatty acids and glycerol. All lipids consist of fatty acid monomers, whereas only fats contain both fatty acids and glycerol, explains the Dallas County Community College Department of Biology.
In popular culture, the terms "fats" and "lipids" are nearly synonymous. The glycerol chain in fats is a monomer biomolecule with three carbons and three hydroxyl groups bound to each carbon atom. A dehydration synthesis reaction creates an ester linkage between the hydroxyl group of glycerol and the terminal carboxyl group of fatty acids, giving polarity to the biomolecule. Rather than being interchangeable with "fats," the biochemical term "lipids" actually refers to molecules only containing fatty acids.