germ vs microbe

germ and microbe both are nouns.

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

As nouns, germ and microbe are synonyms defined as:

germ and microbe: a minute life form (especially a disease-causing bacterium); the term is not in technical use

Other synonyms of germ include bug.

germ (noun)	microbe (noun)
a minute life form (especially a disease-causing bacterium); the term is not in technical use	a minute life form (especially a disease-causing bacterium); the term is not in technical use
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