sea cucumber vs echinoderm

sea cucumber and echinoderm both are nouns.

Word	Noun	Adjective	Verb	Adverb
sea cucumber	Yes	No	No	No
echinoderm	Yes	No	No	No

As nouns, echinoderm is a hypernym of sea cucumber; that is, echinoderm is a word with a broader meaning than sea cucumber:

sea cucumber: echinoderm having a flexible sausage-shaped body, tentacles surrounding the mouth and tube feet; free-living mud feeders
echinoderm: marine invertebrates with tube feet and five-part radially symmetrical bodies

sea cucumber (noun)	echinoderm (noun)
echinoderm having a flexible sausage-shaped body, tentacles surrounding the mouth and tube feet; free-living mud feeders	marine invertebrates with tube feet and five-part radially symmetrical bodies