Cnidaria vs phylum

Cnidaria and phylum both are nouns.

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

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

Cnidaria: hydras, polyps, jellyfishes, sea anemones, corals
phylum: (biology) the major taxonomic group of animals and plants; contains classes

Cnidaria (noun)	phylum (noun)
hydras, polyps, jellyfishes, sea anemones, corals	(biology) the major taxonomic group of animals and plants; contains classes
	(linguistics) a large group of languages that are historically related