phylum Nematoda vs phylum

phylum Nematoda and phylum both are nouns.

Word	Noun	Adjective	Verb	Adverb
phylum Nematoda	Yes	No	No	No
phylum	Yes	No	No	No

As nouns, phylum is a hypernym of phylum Nematoda; that is, phylum is a word with a broader meaning than phylum Nematoda:

phylum Nematoda: unsegmented worms: roundworms, threadworms, eelworms
phylum: (biology) the major taxonomic group of animals and plants; contains classes

phylum Nematoda (noun)	phylum (noun)
unsegmented worms: roundworms, threadworms, eelworms	(biology) the major taxonomic group of animals and plants; contains classes
	(linguistics) a large group of languages that are historically related