mindlessness vs meaninglessness

mindlessness and meaninglessness both are nouns.

Word	Noun	Adjective	Verb	Adverb
mindlessness	Yes	No	No	No
meaninglessness	Yes	No	No	No

As nouns, meaninglessness is a hypernym of mindlessness; that is, meaninglessness is a word with a broader meaning than mindlessness:

mindlessness (noun)	meaninglessness (noun)
the trait of acting rashly and without prudence	the quality of having no value or significance
total lack of meaning or ideas	a message that seems to convey no meaning