Answer: The part of each amino acid that is different from the other is the side chain.
Step-by-step explanation:
Amino acids have three parts: The amino group, the carbon skeleton and the side chain. Every amino acid have the same amino group and carbon skeleton but what distinguishes one from another is the side chain. It is the side chain that determines the chemical properties of each amino acid. Some side chains are aliphatic in nature while some are aromatic, some are acidic while some are basic, thereby making the amino acids polar, hydrophobic, nonpolar, acidic, or basic.