clumsiness vs ineptness

clumsiness and ineptness both are nouns.

Word	Noun	Adjective	Verb	Adverb
clumsiness	Yes	No	No	No
ineptness	Yes	No	No	No

As nouns, clumsiness and ineptness are synonyms defined as:

clumsiness and ineptness: unskillfulness resulting from a lack of training

Other synonyms of clumsiness include awkwardness, ineptitude, maladroitness, slowness.

clumsiness (noun)	ineptness (noun)
the carriage of someone whose movements and posture are ungainly or inelegant	the quality of having the wrong properties for a specific purpose
the inelegance of someone stiff and unrelaxed (as by embarrassment)	unskillfulness resulting from a lack of training
unskillfulness resulting from a lack of training