neglect vs default on

neglect is a noun but default on is not a noun.

Word	Noun	Adjective	Verb	Adverb
neglect	Yes	No	Yes	No
default on	No	No	Yes	No

As verbs, default on is a hyponym of neglect; that is, default on is a word with a more specific, narrower meaning than neglect:

Other hyponyms of neglect include lose track, strike out, default, choke, muff, miss.

neglect (noun)	default on (noun)
failure to act with the prudence that a reasonable person would exercise under the same circumstances
willful lack of care and attention
the trait of neglecting responsibilities and lacking concern
lack of attention and due care
the state of something that has been unused and neglected

neglect (verb)	default on (verb)
leave undone or leave out	fail to pay up
give little or no attention to
fail to attend to
fail to do something; leave something undone