Answer
The four biological macromolecules differ in the subunits which compose them and the purposes which they serve in the cell. Proteins mostly catalyze reactions using the many shapes available to them from the 20 amino acids which compose them while nucleic acids encode information in their nucleotides. Carbohydrates store energy and serve structural roles dictated by the sugars which make them up, and lipids store energy and form lipids bilayers due to their hydrophobic character and the nature of their chemical bonds.
Work Step by Step
To answer this question, review the purpose of each kind of macromolecule and what composes it. Then, give the big picture, what in general does the structure of each macromolecule allow it to do in the cell.
