There is a big difference...
Ground-Control Coil-overs are sleeves that go over your stock strut/shocks to allow you to adjust the height of the spring and thus the ride. These run around $200-300 and are an easy way to be able to lower your car or raise it when needed. The ride isn't as smooth as below, and your struts/shocks will wear out much faster.
A TRUE Coil-over system has the adjustable spring and the strut/shock built together, working together as one. These are generally over $1000, but provide a much better ride and suspension.
