smoothness vs fluency

smoothness and fluency both are nouns.

Word	Noun	Adjective	Verb	Adverb
smoothness	Yes	No	No	No
fluency	Yes	No	No	No

As nouns, smoothness and fluency are synonyms defined as:

Other synonyms of smoothness include eloquence.

smoothness (noun)	fluency (noun)
a texture without roughness; smooth to the touch	the quality of being facile in speech and writing
the quality of having a level and even surface	skillfulness in speaking or writing
the quality of being free from errors or interruptions	powerful and effective language
the quality of being bland and gracious or ingratiating in manner
powerful and effective language