The main differences between altar seaweed and purslane are their attributes, range of distribution, nutritional value, production methods, and appearance. The following is a specific comparison:

Attribute difference :
Altar purslane: commonly known as purslane, wu cai, is a kind of Chinese endemic artificial cultivation of red algae, belongs to the red algae, red cabbage family.

Zizyphus: is a class of seaweed growing in the intertidal zone, belongs to the red algae, the original red algae, red algae, red cabbage, red cabbage family, the distribution range is wide, including frigid, temperate, subtropical and tropical waters.

The distribution range is different :
Altar purslane: mainly distributed in China's Fujian, southern Zhejiang coast, in recent years the breeding range moved north to Jiangsu Nantong and Lianyungang.

Ziziphus purpurea: has a wider distribution range, from the Yellow Bohai Sea to the intertidal zone of the southeast coast, as well as the coasts of Taiwan and Hainan Island.

Production methods are different :
Altar seaweed: can be cultivated artificially, usually need to be cleaned, baked and then packaged, is a non-ready-to-eat product.

Nori: can be dried naturally or processed into ready-to-eat products, such as ready-to-eat seaweed.

The appearance is different:
Seaweed: dried in the sun, it is usually in the form of irregular, loose pieces.

Nori: It can be in the form of round cake-shaped altar seaweed or striped seaweed pressed into thin slices.

The varieties are different :
Altar seaweed: one of the common varieties of seaweed on the market, named after Haidan Island, the main island in Pingtan County, Fujian Province.

Nori: contains a variety of algae, such as striped nori, round nori, sweet nori, etc., of which striped nori is a common type in the north.

Price factor :
Altar seaweed: the price is usually higher, because of its origin, complex processing technology and packaging form and other factors.

Purple cabbage: the price is lower than altar purple cabbage, processing technology is simple.

It is important to note that altar seaweed and nori overlap in terms of nutrient content, but altar seaweed may be richer in certain nutrients, such as iodine and phosphorus. Additionally, alt nori and striped nori differ in appearance and processing methods, with striped nori usually being processed into thin slices of seaweed.