Distinguish between a well and a spring.

Explanation

Rain water sinks into the crust of the earth and seeps through the layers of porous rock. This seepage continues till a layer of non-porous rock is reached. At this level, the water runs along the surface of the rock and may again come out on the surface of the earth as a spring through some cracks or holes in the rock. This is called spring water.
Once the water reaches the non-porous rock, it cannot sink further. Therefore, it gets collected in an underground water pool. If the earth is dug deep enough to reach the underground water table, water comes out. This is called well water.