How does the speed differ from average velocity?

Velocity(speed) is variable over time.(Takes time to get up to speed)
Average velocity is the average over time.

This actually should be under physics, and as it is stated, I'm not really sure what the question is, but if I remember my basic physics...

Velocity has a specific direction. Speed does not. They are not equivalent. Ya' got to be careful about that.

Don't know why I thought they were the same?
Speed and Velocity (http://www.physicsclassroom.com/class/1dkin/u1l1d.cfm)

Speed is indifferent to direction yes, but also don't forget that speed is an instantaneous unit.

Average velocity is the total distance from start divided by the time it took to get there.

For example some can travel 40 miles east at 40 miles per hour and then 40 miles west at 80 miles per hour. The speed east is 40 mph, the speed west is 80 mph, the average speed would be 53 and a third mph, however the average velocity would be 0. This is because the end distance is 0 from the start.

Make sense?

My point was that writing "...velocity (speed)..." is misleading because it indicates that velocity and speed are equivalent in meaning.

Concur with Infojunkie except to point out the only time I've ever seen that example of "velocity" used was to provide an example of the meaning of "velocity", but perhaps I've lived a protected life. ;-)