'Distance' is how far you walk on your afternoon walk, while you cut across the park, go two blocks out of your way to visit a friend, and cross the street several times in both directions to avoid some big-looking dogs. Every step counts for distance. Distance only has a size but no direction, because the direction could change a hundred times during the trip. And from the time you leave home until you return home, the distance could be 5 miles or more.
'Displacement' is very different. Displacement is just the straight-line distance between the starting point and the end point, regardless of the route that was
followed between them. It has a size ... the distance between them, and it also has a direction ... the direction from start to finish. And if you start out from home and return home, then your displacement for that trip is zero, because there's no straight-line distance from the starting point to the end point.
