Environmental science is actually comprehending the environment of a planet. Understanding it's atmospheric properties and seeing the large picture in which all current planetary statistics combined together influence the development and progression of life. Environmental studies comprises the way humans interact with the environment they are subjected to, and fundamentally cause (in the long run). Environmental studies is like scratching the surface of environmental science.
The subject matter is the same; the ways of learning are different. Environmental science applies scientific methods directly to the study of the environment, as Devin tried to describe. Environmental studies could also include experiential learning, literature and film, environmental politics and policy, comparisons of how different cultures relate to their environment, etc.