beluga vs sturgeon

beluga and sturgeon both are nouns.

Word	Noun	Adjective	Verb	Adverb
beluga	Yes	No	No	No
sturgeon	Yes	No	No	No

As nouns, sturgeon is a hypernym of beluga; that is, sturgeon is a word with a broader meaning than beluga:

beluga: valuable source of caviar and isinglass; found in Black and Caspian seas
sturgeon: large primitive fishes valued for their flesh and roe; widely distributed in the North Temperate Zone

beluga (noun)	sturgeon (noun)
valuable source of caviar and isinglass; found in Black and Caspian seas	large primitive fishes valued for their flesh and roe; widely distributed in the North Temperate Zone
small northern whale that is white when adult