Why it is easier to roll a stone up a sloping road than to lift it vertical upwards?

In case of lifting upward, the total weight 'mg' is needed to be overcome by applying a upward force more than 'mg' while in case of rolling in inclined plane, only a component of 'mg' i.e, 'mgsin(theta)' is needed to be overcome to roll the body upward. As mgsin(theta) is less than 'mg' so rolling is easier than lifting.

assume the weight of the object or stone to be W.

As soon as we keep an objech on the slope a component of the weight is balances by the normal component at the contact surface.

think of a stone on non slanted plane , the whole weight is balanced by the normal at the contact surface, rt?.....we don't have to do any thing to hold the stone.

now if we slant the plane by theta angle with respect to horizon some component of weight is balanced by normal(  Wcos(theta)  ) due to contact with surface as explained above,but another component will be tangential to the slope (  Wsin(theta)  ), this some amount of tangential component will be balanced by the friction between the stone and the surface, the remaining you need to apply.

so u need to apply WSIN(theta)- friction, which is certainly less than weight of the stone, so with less force you can move.

when you try to lift a stone you are carrying mg weight. but while rolling it on an inclination of  you carry  which is less than mg. So its easier to roll it on an inclined plane and thats why railway platforms have inclined planes so that we can carry the trolley easily

Earth's gravity on the stone will always oppose you, whether you lift it upwards or roll it up a sloping road. When you lift it upwards there's no one to help you to fight that gravitational force and go against it, and you'll get more tired because you're on your own. But in rolling it up a sloping road, there is something helping you: the road itself (why? because it has a "slope" and its much stiffer than you), and hence you'll get less tired because your "work" has been shared by the road.