microflora vs micro-organism

microflora and micro-organism both are nouns.

Word	Noun	Adjective	Verb	Adverb
microflora	Yes	No	No	No
micro-organism	Yes	No	No	No

As nouns, micro-organism is a hypernym of microflora; that is, micro-organism is a word with a broader meaning than microflora:

microflora: microscopic plants; bacteria are often considered to be microflora
micro-organism: any organism of microscopic size

Other hypernyms of microflora include flora, plant, plant life, microorganism.

microflora (noun)	micro-organism (noun)
microscopic plants; bacteria are often considered to be microflora	any organism of microscopic size