subphylum Craniata vs phylum

subphylum Craniata and phylum both are nouns.

Word	Noun	Adjective	Verb	Adverb
subphylum Craniata	Yes	No	No	No
phylum	Yes	No	No	No

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

subphylum Craniata: fishes, amphibians, reptiles, birds, mammals
phylum: (biology) the major taxonomic group of animals and plants; contains classes

subphylum Craniata (noun)	phylum (noun)
fishes, amphibians, reptiles, birds, mammals	(biology) the major taxonomic group of animals and plants; contains classes
	(linguistics) a large group of languages that are historically related