Ceratostomella ulmi vs fungus

Ceratostomella ulmi and fungus both are nouns.

Word	Noun	Adjective	Verb	Adverb
Ceratostomella ulmi	Yes	No	No	No
fungus	Yes	No	No	No

As nouns, fungus is a hypernym of Ceratostomella ulmi; that is, fungus is a word with a broader meaning than Ceratostomella ulmi:

Ceratostomella ulmi: fungus causing Dutch elm disease
fungus: an organism of the kingdom Fungi lacking chlorophyll and feeding on organic matter; ranging from unicellular or multicellular organisms to spore-bearing syncytia

Ceratostomella ulmi (noun)	fungus (noun)
fungus causing Dutch elm disease	an organism of the kingdom Fungi lacking chlorophyll and feeding on organic matter; ranging from unicellular or multicellular organisms to spore-bearing syncytia