untruth vs fabrication

untruth and fabrication both are nouns.

Word	Noun	Adjective	Verb	Adverb
untruth	Yes	No	No	No
fabrication	Yes	No	No	No

As nouns, fabrication is a hyponym of untruth; that is, fabrication is a word with a more specific, narrower meaning than untruth:

untruth (noun)	fabrication (noun)
a false statement	the act of making something (a product) from raw materials
	the act of constructing something (as a piece of machinery)
	writing in a fictional form
	the deliberate act of deviating from the truth
	a deliberately false or improbable account