Difference in species and genus.

Undaria pinnatifida brown algae phylum, brown subclass, kelp order, winged algae family, wakame genus. Plants belonging to the seaweed, leaf green pinnate lobes, leaf blade is thinner than the kelp, the shape of a large broken sunflower fan, but also like the kelp, so it takes its name.

Porphyra (Porphyra), is in the sea in the mutual algae collectively. Red algae class, red cabbage family. Algae body is membranous, known as chloroplasts, purple or brownish green, shape varies with species, Porphyra is a marine red algae. Chloroplasts consist of a layer of cells embedded in a thin layer of gelatinous, dark brown, red or purple, purslane fixer discoid, pseudoroot filamentous, grow on rocks in the intertidal zone of the shallow sea.

The wakame is a seaweed plant. And nori belongs to the marine red algae.

Why is nori cheap seaweed expensive

Because there is a big difference in this aspect of the processing, nori is very simple to do, but in the production of seaweed need to go through the selection, but also after crushing, high-temperature pressurization, de-watering baking and other such procedures in order to make out, but also to add some seasonings, flavor! The cost will also be much higher, so the price will be more expensive than nori.