I have explained in the N85 V1 thread, ok i copy and paste here

there are 4 GPS locking option setting in the positioning option (tool-connection-gps data- option-positioning setting- positoning method)

1. blue-tooth GPS --- need to connect to external blue-tooth enable GPS device - mostly off
2. Assisted GPS --- using GPRS connectivity to speed up in locating your position, IMO AGPS will switch off as soon as your IGPS is connected to satellite --- minimal charge -(refer to my attached image for my 3 different routes) -recommended to switch on because it is useful in rainy, cloudy weather

3. Integrated GPS --- using your integrated GPS with directly connectivity with satellite -- no charge at all - must switch on
4. Network base GPS --- using your network provider for data transfer of GPS details including traffic/weather info -- charge according to total data package - mostly off , only on if you have unlimited data rate in your service provider.

no matter which software/app you use these 4 option are the one that determine your GPS locking method -even in garmin.