Can someone explain how to force GPS navigation into my bluetooth earpiece?

I don't understand why BT GPS Naviation works for my bluetooth speaker,
but it doesn't work for my bluetooth earpiece.

Debugging on my Samsung Galaxy S3, I see something strange (to me):
http://farm8.staticflickr.com/7402/1...35787e7b_o.png

What I found, is there are (apparently?) two different kinds of BT!
a) Motorola Roadster (*connected to phone and media audio*)
b) Samsung HM1300 (*connected to phone audio*)

Hmmmmmm......
Are there two *different* kinds of bluetooth audio (media & phone)?

If that is the problem, how do I get the right kind of GPS audio into my
bluetooth earpiece just like it does with my bluetooth visor speaker?