All the pellets i've tried are heavier than water and won't float. I heat my house with pellets and the only advantage over wood that I can see is that they are in a convenient form for the stove to feed in small amounts. Hi Ray, The difference is mostly in moisture content. The pellets also have a small amount of resin in them which raises the BTU value very slightly over non resinous woods. Good dry wood has about the same heat value as pellets.
Pellets are quite interesting in their density.
A five gallon pail of wood for my steam outboard has about 9 pounds of wood in it, while 5 gallons of pellets is more like 40 pounds. All the pellets i've tried are heavier than water and won't float.