What is the difference between Artisan Well and Spring?

Whenever it rains, the soil absorbs the water. The water goes down into the ground. When it reaches down to such as place where a porous rock or sand is surrounded by hard rocks, it is collected there. A pressure is built up due to hard rocks around it. When we dig a hole in the ground and it gives an opening to the underground water, it gushes out. Artisan wells are always lower than the place at which water is absorbed by the soil.

On the other hand, we do not need to bore a hole in the ground for finding spring.