Ma'am, what's the actual difference between breathing and respiration? My friend says they're the same, but I think they're not.

This is a very common point of confusion! Breathing and respiration are definitely not the same. Breathing is a physical, mechanical process involving the inhalation of oxygen-rich air and the exhalation of carbon dioxide-rich air. It's about gas exchange between the body and the environment, primarily facilitated by the lungs. Respiration, on the other hand, is a biochemical process that occurs inside the cells of an organism. It's the process where glucose (food) is broken down in the presence or absence of oxygen to release energy (ATP) for various life activities. For example, aerobic respiration occurs in mitochondria: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{Energy (ATP)}$. So, breathing supplies the oxygen needed for aerobic respiration, but respiration is the actual energy-releasing process.