I would like to recommend you to observe those with a microscope in detail.
Although I do not know how those powders are made from each row materials, as far as “wood” is xylem of angiosperms or gymnosperms, major part of powder from those wood should be fragments of cell walls of wood fibers or tracheids. In contrast, powder from coconut shell may probably be cell walls of parenchymatous cells which may be quite different from those of wood fibers in morphological and also chemical structure.