The GPS stands for Global Positioning System, while AGPS means Assisted Global Positioning System. The GPS was earlier built by the military to provide an edge on the battlefield. The GPS device gets a signal from any four of the thirty-two satellites that orbit the earth, and provide the required information to the user.
The AGPS, on the other hand, provides better information than the initial GPS with the help of an assistance server. The standalone GPS has been in existence long before the invention of the AGPS, and it is usually used in cars, planes, boats, and the likes. The AGPS is mostly known to be used in mobile phones due to the present access to the data connection.
The AGPS is more reliable than the GPS when it comes to providing the correct location. The AGPS, generally, seems to operate better in performance when compared to the GPS, as it also works faster than the latter.