What is difference between contour barrier …

In terracing, wide steps are cut around the slopes of hills to prevent soil erosion. Contour ploughing follows the “natural shape” of the slope without altering it. Terrace farming alters the shape of the slope to produce flat areas that provide a catchment for water.
Terrace Farming: In Steep slope region when farming is done on flat surface. So, where does this flat surface come from? You made it available for yourself by using machines or manually. :) Just Think of Steps of your house. Your Dearest child insists to plant something on Every step. Terrace Farming it is somewhat bigger in size. You can visualize it.

Contour ploughing: In Steep slope region when you want to do farming without making available a flat surface for you because you’re too lazy to do all this work. so whats the solution now? Umm, well, now you are going to plant something down the slope without doing extra labor. An idea pops up into your mind to use physical barrier (Stones, sand or trenches) to prevent surface runoff.