The distinction follows the wood species used: coniferous (softwood) species such as pine, spruce, and fir fall under 470311 or 470321, while nonconiferous (hardwood) species such as eucalyptus, birch, and acacia fall under 470319 or 470329. Mill certificates and technical data sheets typically identify the fiber species, and customs may request them to verify classification.

Bleaching stage affects both classification and end use. Unbleached pulp retains more lignin and is darker, making it suitable for packaging grades where strength matters more than brightness. Semibleached and fully bleached pulps have lower lignin content and higher brightness, qualifying them for printing, writing, and tissue grades. The subheadings track this distinction, so the mill's bleaching sequence determines the correct line.