What's the difference between distance and displacement

Distance is a scalar, meaning it only has a magnitude. Displacement is a vector, meaning that it has both magnitude and direction. For instance, distance can state that I am "x" metres away from a point, displacement would state that I am "x" metres away in a "y" direction. If you travel away from a point then return, you have travelled a non zero distance, but your displacement is zero as you have returned to your original position.