What's different between speed and velocity?

Speed refers to how fast an object is going when the acceleration is constant.

Velocity is how fast and object is going and the direction it's heading. It can be positive or negative. Negative usually means the the object is going backwards, or that the object is falling at the instant in time ( for ex. a ball falling)

The units for velocity is expressed in m/s

People get this confused and think the units are m/s^2 when in fact, this is the units for acceleration.

Hope this helps

The way my wife drives there is no difference.Very,very fast

Speed just tells you how fast something is going, while Velocity also shows direction.

e.g. I start at point A (in a car) and reverse at 25 km/h. My speed is 25 km/h, but my velocity is -25km/h because I am moving backwards relative to the starting point.

Similarly, if i was moving forwards, my velocity would be +25km/h

Speed is the rate at which an object is moving.

ex.) 35 miles per hour

Velocity is the rate at which the object is moving, WITH A DIRECTION

ex.) 35 miles per hour NORTH

That's the difference.