append vs insert

append is not a noun while insert is a noun.

Word	Noun	Adjective	Verb	Adverb
append	No	No	Yes	No
insert	Yes	No	Yes	No

As verbs, insert is a hyponym of append; that is, insert is a word with a more specific, narrower meaning than append:

Other hyponyms of append include slip in, sneak in, stick in, toss in.

append (noun)	insert (noun)
	(film) a still picture that is introduced and that interrupts the action of a film
	(broadcasting) a local announcement inserted into a network program
	an artifact that is inserted or is to be inserted
	a folded section placed between the leaves of another publication

append (verb)	insert (verb)
state or say further	place, fit, or thrust (something) into another thing
fix to; attach	insert casually
add to the very end	put or introduce into something
	fit snugly into