nanometre vs millimicron

nanometre and millimicron both are nouns.

Word	Noun	Adjective	Verb	Adverb
nanometre	Yes	No	No	No
millimicron	Yes	No	No	No

As nouns, nanometre and millimicron are synonyms defined as:

nanometre and millimicron: a metric unit of length equal to one billionth of a meter

Other synonyms of nanometre include micromillimeter, micromillimetre, nanometer, nm.

nanometre (noun)	millimicron (noun)
a metric unit of length equal to one billionth of a meter	a metric unit of length equal to one billionth of a meter