epipsammon vs benthos

epipsammon and benthos both are nouns.

Word	Noun	Adjective	Verb	Adverb
epipsammon	Yes	No	No	No
benthos	Yes	No	No	No

As nouns, benthos is a hypernym of epipsammon; that is, benthos is a word with a broader meaning than epipsammon:

epipsammon: Microscopic flora and fauna found on the surface of and/or attached to sand grains.
benthos: organisms (plants and animals) that live at or near the bottom of a sea, lake, river or stream

epipsammon (noun)	benthos (noun)
Microscopic flora and fauna found on the surface of and/or attached to sand grains.	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