Green Boxes on the street, are they all BT?

[TheGamE]

I heard that if you are getting broadband from BT, make sure the 'Green Box' is close.

I have a green box not more than 20 yards from my house. I just can't tell whether it is BT or not.
I checked the service from their website and for the 78mb connection I am estimated at 76mb. My guess is it is the BT box to get such good connection. But then again, it is from BT website, they may be over advertising.

Is there a way to tell if it is a BT box?

Thanks.