drop-off vs decrease

drop-off and decrease both are nouns.

Word	Noun	Adjective	Verb	Adverb
drop-off	Yes	No	No	No
decrease	Yes	No	Yes	No

As nouns, drop-off and decrease are synonyms defined as:

Other synonyms of drop-off include lessening.

drop-off (noun)	decrease (noun)
a change downward	the act of decreasing or reducing something
a steep high face of rock	the amount by which something decreases
a noticeable deterioration in performance or quality	a change downward
	a process of becoming smaller or shorter

drop-off (verb)	decrease (verb)
	decrease in size, extent, or range
	make become smaller