Here's why:

* Instantaneous Speed: This is your speed at a specific moment in time. It's the speed the speedometer displays right now.

* Average Speed: This is the total distance traveled divided by the total time taken. It's not what the speedometer shows, but rather a calculation over a longer period.

In simpler terms:

* The speedometer tells you how fast you're going *right now*.

* Average speed considers the entire trip and how long it took you.