A rate is a specific kind of ratio that compares two different units of measurement, while a ratio simply compares two quantities of the same kind.
For example, when we say that a car travels at a speed of 60 miles per hour, we are expressing a rate. Here, we are comparing the distance (miles) to time (hours) — two different units. In contrast, if we were to compare the number of apples to oranges, say 5 apples to 3 oranges, we would express this as a ratio of 5:3 or 5/3. Both quantities are of the same kind (fruit), making it a simple ratio.
In summary, all rates are ratios, but not all ratios are rates. Rates provide more specific information by linking different types of measurements, which makes them useful in fields like finance, medicine, and science.