magnitude is basically the measurement,
distance is the total ground that you covered. If you started at point a, walked ten feet to point b, then turned around and walked 13 feet to point c, your total distance would be 10 + 13 = 23 feet
using the same example, your displacement is only how far away you are from the starting point. So point b doesnt matter, because you end up passing through point a again (I hope that made sense :o) and the magnitude of your displacement would be 3 feet