Amazon lists the BG10 much higher, at 150,000.
I'd take all those BTU claims with a large pack of salt. Like HP, it tends to be wildly inflated.
IIRC, a few years ago Bobby ('our' Bobby, from BrewHardware) had posted a BTU test for burners. He may have a Youtube vid on it.
In short, you clean the orifice and other channels, adjust the burner to maximum power, all blue, no yellow flames etc. You weigh the tank, and 10-20' later you weigh it again. The difference is the amount of gas burned, and thus the maximum BTUs generated.
At the time, I think the Blichmann came in highest, but don't remember the actual BTU rating, could have been around 75-90k or so.
Many burners using that same large banjo burner will come in similarly.
Efficiency can be measured too, at the same time, how long it takes to heat a gallon (or 5, 7, 10 gallons etc.) in your kettle setup to a certain temperature, e.g., from 80-130F or 150-200F. Theoretical BTUs required vs. actual BTUs (e.i. gas weight) used.
That windscreen around the burner and (close) proximity of the burner to the bottom of the kettle are essential factors in high efficiency. If it's a windy day, put a wind screen around your setup, or boil in the wind shade.