heedlessness vs inadvertency

heedlessness and inadvertency both are nouns.

Word	Noun	Adjective	Verb	Adverb
heedlessness	Yes	No	No	No
inadvertency	Yes	No	No	No

As nouns, heedlessness and inadvertency are synonyms defined as:

heedlessness and inadvertency: the trait of forgetting or ignoring your responsibilities

Other synonyms of heedlessness include inadvertence, unmindfulness.

heedlessness (noun)	inadvertency (noun)
the trait of forgetting or ignoring your responsibilities	the trait of forgetting or ignoring your responsibilities
the trait of acting rashly and without prudence
a lack of attentiveness (as to children or helpless people)