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The carboxylic acid-derived ester linkages in a triglyceride or typical glycerophospholipid have the form $\mathrm{R}-\mathrm{C}(=\mathrm{O})-\mathrm{O}-{\mathrm{R}}^{\prime }$. Here the acyl group is attached through oxygen to the glycerol-derived part. See IUPAC Blue Book, P-65.6: esters.

A fatty acid is a carboxylic acid with a hydrocarbon chain. Its chain supplies much of the hydrophobic region when incorporated into a triglyceride or typical glycerophospholipid. See Biology 2e: fatty acids.

Glycerol has three carbon chemical atoms and three $\mathrm{OH}$ groups. It supplies the scaffold of triglycerides and glycerophospholipids, but is not itself a long hydrocarbon chain. See Biology 2e: glycerol.

Lipids are a chemically diverse family of chemical substances, conventionally associated with biological origin and solubility in nonpolar solvents. They include triglycerides, phospholipids, and cholesterol. The name does not specify one molecular formula, one repeating monomer, or one kind of polymer. Some lipids have both hydrophilic and hydrophobic regions rather than being uniformly nonpolar. See IUPAC Gold Book: lipids.

Structure explains the different jobs. A triglyceride has three fatty acid-derived acyl groups attached to glycerol and serves as an energy store. A typical glycerophospholipid instead combines two such chains with a phosphate-containing head, making it an amphiphile suited to a lipid bilayer. Cholesterol has a different structure and also contributes to cell membrane properties. Thus a lipid is a chemical building material, while a lipid bilayer is an organization of many molecules. See Clark, Douglas and Choi, Biology 2e, 3.3: lipid structures and functions.

A triglyceride contains glycerol joined to three fatty acid-derived acyl groups through ester linkages. Compare the three chains with the two-chain, phosphate-headed glycerophospholipid illustrated below. See Biology 2e: fats and oils.