Coal-based foams are stronger and denser but do not conduct heat as well. Lignin-based foams are strong yet lightweight, with low density and excellent thermal conductivity. Different products equals different marketplaces within same industry.
"Various feedstocks have been used as the precursors for carbon foam production including various pitches, asphalts, foamed synthetic plastics, coals, and coal extracts. The properties of the carbon foams depend on both the raw material characteristics and the selected process conditions. For example, carbon foams from pitches show good thermal conductivity and low density but poor mechanical strength; coal-based foams have good mechanical strength and higher density, but lower thermal/electrical conductivity. Some carbon foams have been formed from ligninsulfonates and ligninsulfonate/polymer compositions. However, such carbon foams exhibited low density and very low mechanical strength."