Although they both belong to the phylum Brown Algae and the order Kelp, kelp belongs to the family Kelpaceae, while kombu belongs to the family Hymenoptera. In addition, their growing environments are also different: kombu generally grows on rocks and requires stronger currents and light conditions, while kelp grows in stony or gravelly waters on the seabed and requires softer currents and weaker light conditions. Morphologically, kombu is more elongated; while kelp has broad, thick leaves with multiple branches, presenting a tree-like form.