Location and Security settings

[navigator]

Just got my new RAZR yesterday. I upgraded from the original Droid.

What is the difference between "Google location service," "Standalong GPS Service" and "VZW location service?" Do I need to use all three? What is the effect on the battery?

I turned on the toggle "power control widget." I assume the third one from the left that look like a satilite is one of the gps services? Which one?

Thanks