king crab vs Alaska crab

king crab and Alaska crab both are nouns.

Word	Noun	Adjective	Verb	Adverb
king crab	Yes	No	No	No
Alaska crab	Yes	No	No	No

As nouns, king crab and Alaska crab are synonyms defined as:

king crab and Alaska crab: large edible crab of northern Pacific waters especially along the coasts of Alaska and Japan

Other synonyms of king crab include Alaska king crab, Alaskan king crab, Paralithodes camtschatica.

As nouns, king crab and Alaska crab are synonyms defined as:

king crab and Alaska crab: meat of large cold-water crab; mainly leg meat

Other synonyms of king crab include Alaska king crab, Alaskan king crab.

king crab (noun)	Alaska crab (noun)
large edible crab of northern Pacific waters especially along the coasts of Alaska and Japan	large edible crab of northern Pacific waters especially along the coasts of Alaska and Japan
large marine arthropod of the Atlantic coast of North America having a domed carapace that is shaped like a horseshoe and a stiff pointed tail; a living fossil related to the wood louse	meat of large cold-water crab; mainly leg meat
a large spider crab of Europe
meat of large cold-water crab; mainly leg meat