phylum Mollusca vs phylum

phylum Mollusca and phylum both are nouns.

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

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

phylum Mollusca: gastropods; bivalves; cephalopods; chitons
phylum: (biology) the major taxonomic group of animals and plants; contains classes

phylum Mollusca (noun)	phylum (noun)
gastropods; bivalves; cephalopods; chitons	(biology) the major taxonomic group of animals and plants; contains classes
	(linguistics) a large group of languages that are historically related