mycobacterium vs true bacteria

mycobacterium and true bacteria both are nouns.

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

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

mycobacterium: rod-shaped bacteria some saprophytic or causing diseases
true bacteria: a large group of bacteria having rigid cell walls; motile types have flagella

Other hypernyms of mycobacterium include eubacteria, eubacterium.

mycobacterium (noun)	true bacteria (noun)
rod-shaped bacteria some saprophytic or causing diseases	a large group of bacteria having rigid cell walls; motile types have flagella