GPS is a satellite constellation developed by the US for military use that later became accessible to civilians. GLONASS is Russia's global navigation satellite system accessible for both military and civilian use. The key differences are that GPS satellites use the same codes but different frequencies to communicate, while GLONASS uses the same frequencies but different codes. Additionally, GPS has 32 satellites in 6 orbital planes at 20,180 km altitude and 55 degrees from the equator, while GLONASS has 24 satellites across 3 orbital levels at 19,100 km altitude and 64.8 degrees from the equator.