germ vs microorganism

germ and microorganism both are nouns.

Word	Noun	Adjective	Verb	Adverb
germ	Yes	No	No	No
microorganism	Yes	No	No	No

As nouns, microorganism is a hypernym of germ; that is, microorganism is a word with a broader meaning than germ:

germ: a minute life form (especially a disease-causing bacterium); the term is not in technical use
microorganism: any organism of microscopic size

Other hypernyms of germ include micro-organism.

germ (noun)	microorganism (noun)
a minute life form (especially a disease-causing bacterium); the term is not in technical use	any organism of microscopic size
a small apparently simple structure (as a fertilized egg) from which new tissue can develop into a complete organism
anything that provides inspiration for later work