Undaria and nori are different species of seaweed. Although they are somewhat similar in appearance, they come from different plant families. Wakame belongs to the Ulva family, Undariaceae (Latissima), while nori belongs to the Rhodophyta, Rhodophyta, Porphyra (Porphyra). They differ in their morphological features, growing environment and uses. Undaria usually shows a broad and flat band structure and grows mostly on rocks or shells, while purslane shows a lamellar structure and grows mostly on rocks or other marine substrates.