If we push or pull the object exactly horizontal then frictional force will be same . Often, we
push at a downward angle. Only part of your applied force is horizontal. The other part is vertically down. This adds to the object's weight and the Normal force increases and then so will friction., as it is proportional to the normal force. When we pull, we frequently pull at an upward angle. The vertical part of our applied force is up which subtracts from the object's weight, resulting in a smaller Normal force and a smaller frictional force.