I am a member of the IWCS..(International Wood Collectors Society)...and have this rather single-minded passion to find correct info about wood whenever possible...(I make turned items..of MANY different wood of the world...and in general the case seems to be as BOTH Bill Cameron and Liam's brother say....BRW can be heavier, but not necessarily....and the same species of wood can vary widely from tree to tree and even from different cuts in the SAME tree...so, although you might be able to generalize that, of 100 instruments of each wood, you would find MORE BRW than IRW to your liking, you must evaluate them individually..

(I have had 2 bowls from the same log behave in totally different manner and exhibit different coloring and density)

here are 2 different levels in one of the BEST sources of information...The USDA Forest Products Labratory..in Madison , Wisconsin...

Data on BRW

Data on IRW

menu for looking at LOTS of wood

back a couple of levels to menu for other stuff about the wood..