Another big difference is that GPS has more commercial use. However, Glonass is more accurate than GPS with advantage of 2 meters of accuracy. But, Glonass does not have that strong coverage as GPS does.
Space Usage
Many people have used the Global Positioning System to find their location on earth. Nowadays, this satellite network can help other satellites to find their way in space. It can also prevent the orbiting communication devices to collide.
The common way to control satellites is done with controllers on the ground. Thus, they would monitor any changes that are done by the satellite using radio transmissions. But, this was in the history of GPS development.
Today, few low-flying satellites, that are positioned on a few hundred kilometers, have installed GPS receivers which determines their positions. This is done instantly and also can adjust their orbits fast and cheaper than before when using the ground controllers.
