The groundwater and the aquifers essentially fall into the same category, as both of them are part of the underground freshwater reserves (though in some cases they can be saline as well). The groundwater tends to be mixed with ground very often. It also has the tendency to move inside the ground, making holes into the rocks or the ground and trying to find its way out on the surface. The aquifers, on the other hand, are much more static. They are larger bodies of water that are located inside the ground. In a way, they are like underground lakes, or rather reservoirs of water. The connection between these two, apart from being underground water bodies, is that the groundwater is often supplying the aquifers with water, thus recharging the water that they have lost though human usage or evaporation.
