benthonic zone vs benthos

benthonic zone and benthos both are nouns.

Word	Noun	Adjective	Verb	Adverb
benthonic zone	Yes	No	No	No
benthos	Yes	No	No	No

As nouns, benthonic zone and benthos are synonyms defined as:

benthonic zone and benthos: a region including the bottom of the sea and the littoral zones

Other synonyms of benthonic zone include benthic division.

benthonic zone (noun)	benthos (noun)
a region including the bottom of the sea and the littoral zones	organisms (plants and animals) that live at or near the bottom of a sea, lake, river or stream
	a region including the bottom of the sea and the littoral zones