runniness vs fluidness

runniness and fluidness both are nouns.

Word	Noun	Adjective	Verb	Adverb
runniness	Yes	No	No	No
fluidness	Yes	No	No	No

As nouns, runniness and fluidness are synonyms defined as:

Other synonyms of runniness include fluidity, liquidity, liquidness.

runniness (noun)	fluidness (noun)
the property of flowing easily	the property of flowing easily
	a changeable quality