eelworm vs roundworm

eelworm and roundworm both are nouns.

Word	Noun	Adjective	Verb	Adverb
eelworm	Yes	No	No	No
roundworm	Yes	No	No	No

As nouns, roundworm is a hypernym of eelworm; that is, roundworm is a word with a broader meaning than eelworm:

eelworm: any of various small free-living plant-parasitic roundworms
roundworm: unsegmented worms with elongated rounded body pointed at both ends; mostly free-living but some are parasitic

Other hypernyms of eelworm include nematode, nematode worm.

eelworm (noun)	roundworm (noun)
any of various small free-living plant-parasitic roundworms	unsegmented worms with elongated rounded body pointed at both ends; mostly free-living but some are parasitic
	infections of the skin or nails caused by fungi and appearing as itching circular patches