A remote-controlled quadcopter flies along a winding path in a field.

It moves from position P to position Q in 1.51.51.5 minutes, covering a total path distance of 18.0 m18.0\text{ m}18.0 m. The start and finish positions are 4.5 m4.5\text{ m}4.5 m apart in a straight line.
Explain why the average speed and average velocity of the moving quadcopter are different from one another.
You should include calculations in your answer.