sea cucumber vs holothurian

sea cucumber and holothurian both are nouns.

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

As nouns, sea cucumber and holothurian are synonyms defined as:

sea cucumber and holothurian: echinoderm having a flexible sausage-shaped body, tentacles surrounding the mouth and tube feet; free-living mud feeders

sea cucumber (noun)	holothurian (noun)
echinoderm having a flexible sausage-shaped body, tentacles surrounding the mouth and tube feet; free-living mud feeders	echinoderm having a flexible sausage-shaped body, tentacles surrounding the mouth and tube feet; free-living mud feeders