benthos vs epipelon

benthos and epipelon both are nouns.

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

As nouns, epipelon is a hyponym of benthos; that is, epipelon is a word with a more specific, narrower meaning than benthos:

benthos: organisms (plants and animals) that live at or near the bottom of a sea, lake, river or stream
epipelon: cyanobacteria and eukaryotic algae that live on or in association with fine-grained substrata.

Other hyponyms of benthos include marine benthos, epipsammon, endopsammon, epixylon, merobenthos, microbenthos.

benthos (noun)	epipelon (noun)
organisms (plants and animals) that live at or near the bottom of a sea, lake, river or stream	cyanobacteria and eukaryotic algae that live on or in association with fine-grained substrata.
a region including the bottom of the sea and the littoral zones