nitrobacteria vs true bacteria

nitrobacteria and true bacteria both are nouns.

Word	Noun	Adjective	Verb	Adverb
nitrobacteria	Yes	No	No	No
true bacteria	Yes	No	No	No

As nouns, true bacteria is a hypernym of nitrobacteria; that is, true bacteria is a word with a broader meaning than nitrobacteria:

nitrobacteria: soil bacteria that convert nitrites to nitrates
true bacteria: a large group of bacteria having rigid cell walls; motile types have flagella

Other hypernyms of nitrobacteria include eubacteria, eubacterium.

nitrobacteria (noun)	true bacteria (noun)
soil bacteria that convert nitrites to nitrates	a large group of bacteria having rigid cell walls; motile types have flagella