The BR felt thinner, both the canvas outer and the wool/alpaca liner. I also bought it in a size medium, so trying to get any layer under it was a struggle, which may have been the issue, but I used it just a few times before deciding it wasn't for me, and sold it, so I can't give you actual data at this point.What makes Buzz Rickson cooler than ironheart? Seems like the same construction


