From a chemical view, the main groupings of biomolecules are proteins, nucleic acids, lipids, and carbohydrates. Alone among these groups, lipids are not polymers -- therefore the information contained in their molecular structure must be of a different kind than monomer type within a polymer sequence. Because biological membranes are physical mixtures of many components, the thermodynamics of mixing and phase behavior provides clear guidance for design and interpretation of experiments.
Although textbooks properly explain the principal categories of lipid types, thousands of different lipids occur in Nature, and it is daunting to think that even small differences in structure could be significant, could carry information. Yet, we know that adenylate and deoxyadenylate, glucose and galactose, leucine and isoleucine have different information in their structures. We would likely err should we think that small differences in lipid structure have no role in living systems.