In short
Speed is a scalar quantity that measures how fast an object moves (magnitude only); velocity is a vector quantity that measures how fast and in which direction it moves.
Speed vs Velocity — Comparison Table
| Basis | Speed | Velocity |
|---|---|---|
| Quantity type | Scalar | Vector |
| Direction | Not considered | Considered |
| Definition | Distance / time | Displacement / time |
| Can be zero? | Zero only if at rest | Can be zero even while moving (round trip) |
| SI unit | m/s | m/s |
Want to understand this fully? Read the Physics notes on this chapter.