molecule vs grinding

molecule and grinding both are nouns.

Word	Noun	Adjective	Verb	Adverb
molecule	Yes	No	No	No
grinding	Yes	No	No	No

As nouns, grinding is a hyponym of molecule; that is, grinding is a word with a more specific, narrower meaning than molecule:

Other hyponyms of molecule include grain, chylomicron, flyspeck, identification particle.

molecule (noun)	grinding (noun)
(physics and chemistry) the simplest structural unit of an element or compound	a harsh and strident sound (as of the grinding of gears)
(nontechnical usage) a tiny piece of anything	material resulting from the process of grinding
	the wearing down of rock particles by friction due to water or wind or ice