Your mapping device has a GPS reciver, and you think that proves that GPS has maps?
How exactly does a specimen of your observational prowess even find the power button on a computer?
I don't have a "mapping device"; I have a GPS device. It is loaded with maps on an SD card. That's how it gets updates.
All the satellites tell it is its present position. The database does the rest. Don't worry your pointed little head about how it works -- there's a little man in there that draws a map with a big blue crayon, awright?
You have a mapping device with a GPS receiver. All the information you get from GPS is latitude, longitude, and elevation. You get that from comparing the radio signals from 4 of the 24 satellites that are broadcasting signals, comparing the distance to each one, and using trilateration to figure out its location on an imaginary globe. The recivers can be made small enough to fit inside a USB stick, so they easily fit into cell phones and mapping devices designed to use the data to pinpoint your location an a map.
NO SHIT SHERLOCK.