eelworm vs nematode worm

eelworm and nematode worm both are nouns.

Word	Noun	Adjective	Verb	Adverb
eelworm	Yes	No	No	No
nematode worm	Yes	No	No	No

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

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

Other hypernyms of eelworm include nematode, roundworm.

eelworm (noun)	nematode worm (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