Confused about stock head unit
 

Long story short, My friend has an 04 Jetta with a Monsoon head unit. I have an 03 Golf with what I presume is a Monsoon head unit.

How can I tell if my head unit, which has been replaced, and is separate from the car, is a Monsoon unit?

And if so, can it be put into the Jetta as a replacement unit?

My unit says "Premium 6" and "US" along with the model and serial number. Is there any indicator there?