bogieb
Minister of Fire
The difference in weight is marginal, and really can't contribute to anything proven. It simply could be that one product has 1.5% more moisture content over the other. Which in turn, would mean less heat, and more smoke.
Although a true statement, the heavier bags of pellets have burned nicely for me, with less ash and smoke than the lighter bags of pellets. There is close to a 4% difference between the lightest bags and heaviest bags that I have gotten my hands on. And, the lightest pellets were not the cheapest, so I paid more, for less poundage, less heat and more work (for example - this year I have to empty the P61a ash can every 2 weeks; last year I could go easy 3 and up to 4 weeks).
However, I would agree there is absolutely no correlation between weight of bags and heat output or ashiness - it just happened to work out that way for me this year.