false vs insincere

false and insincere both are adjectives.

Word	Noun	Adjective	Verb	Adverb
false	No	Yes	No	Yes
insincere	No	Yes	No	No

false (adjective)	insincere (adjective)
not in accordance with the fact or reality or actuality	lacking sincerity
not genuine or real; being an imitation of the genuine article
adopted in order to deceive
designed to deceive
(used especially of persons) not dependable in devotion or affection; unfaithful
arising from error
inaccurate in pitch
deliberately deceptive
erroneous and usually accidental
inappropriate to reality or facts

false (adverb)	insincere (adverb)
in a disloyal and faithless manner