neglectfulness vs carelessness

neglectfulness and carelessness both are nouns.

Word	Noun	Adjective	Verb	Adverb
neglectfulness	Yes	No	No	No
carelessness	Yes	No	No	No

As nouns, carelessness is a hypernym of neglectfulness; that is, carelessness is a word with a broader meaning than neglectfulness:

neglectfulness: the trait of neglecting responsibilities and lacking concern
carelessness: the quality of not being careful or taking pains

Other hypernyms of neglectfulness include sloppiness.

neglectfulness (noun)	carelessness (noun)
the trait of neglecting responsibilities and lacking concern	failure to act with the prudence that a reasonable person would exercise under the same circumstances
	the quality of not being careful or taking pains