eelworm vs vinegar eel

eelworm and vinegar eel both are nouns.

Word	Noun	Adjective	Verb	Adverb
eelworm	Yes	No	No	No
vinegar eel	Yes	No	No	No

As nouns, vinegar eel is a hyponym of eelworm; that is, vinegar eel is a word with a more specific, narrower meaning than eelworm:

eelworm: any of various small free-living plant-parasitic roundworms
vinegar eel: minute eelworm that feeds on organisms that cause fermentation in e.g. vinegar

Other hyponyms of eelworm include Anguillula aceti, Turbatrix aceti, vinegar worm.

eelworm (noun)	vinegar eel (noun)
any of various small free-living plant-parasitic roundworms	minute eelworm that feeds on organisms that cause fermentation in e.g. vinegar