What is the differ between runoff and ground water?

Answer 1

one is reused and the other stuck underground

Answer 2

The best way to understand the difference between run-off water and ground water is to give examples.

Ground Water - Under the earth's surface are networks of old channels. Some are dry and were old streams that flowed underground, as well as in some places formed natural springs on the earth's surface. These springs are where Indians and Colonists stopped to get water, or even built towns nearby. But sources of ground water change, just like on the earth's surface. Some dry up, and later can flood again. Some carve out new channels. When people drill water wells, they are attempting to 'tap into' these sources of ground water. When a well 'goes dry' it means the underground channel has 'gone dry' or the pathway the water took underground changed. That's why people sometimes needed to drill new water wells. In another example closer to the earth's surface, sometimes you can dig with a shovel and after one or two shovel-fulls, you find the hole naturally fills with water. The ground water is trapped in the soil, even if the ground just above seems dry.

Run-off Water - We have all watched it rain and seen or heard rain water as it hits the roof of a house, travels through gutters, and out downspouts. We may see water from downspouts run across our driveway, to the lowest point at the street (usually in the gutter alongside the street), then continue flowing in a downward direction. Most times, the water finds a grate where the water flows to an underground sewer, and from the sewer it goes to a waste water treatment plant. We've also seen people washing cars in their driveways. The water flows downward, into the street... and again, ends up at sewers and water waste treatment plants... Or water from streets flows off into grass/weeds or into streams or creeks nearby. This is one reason people get upset, because run-off water that contains cleaning agents or detergents can get into fresh water streams and creeks and kill fish and wildlife.

Geologists estimate there is more ground water that humans cannot reach or discover. The new drilling of Marcelles Shale is of concern because these drill sites can disturb the natural channels of ground water. Also the brine used to drill these sites ends up being pumped down another drilled well, where it will mix with underground 'ground water' and contaminate the formation of natural springs and man-made water wells. So it is important to remember that anything we do on the surface can create run-off that can affect ground water.