1, the king crab belongs to the family Lithopodidae of Decapoda, and the common one is Kamchatka, which is not a real crab. Long-legged crab belongs to the fan crab family of Decapoda, short-tailed suborder, also known as Alaska emperor crab.

2. The distribution areas are different. Long-legged crabs are mainly distributed in cold sea areas such as the northern Pacific of North America, the deep sea of Bering Sea and Japan Sea, while king crabs are mainly distributed in cold sea areas such as the North Pacific and Arctic Sea.