preoccupancy vs preoccupation

preoccupancy and preoccupation both are nouns.

Word	Noun	Adjective	Verb	Adverb
preoccupancy	Yes	No	No	No
preoccupation	Yes	No	No	No

As nouns, preoccupancy and preoccupation are synonyms defined as:

preoccupancy and preoccupation: the act of taking occupancy before someone else does

As nouns, preoccupancy and preoccupation are synonyms defined as:

preoccupancy and preoccupation: the mental state of being preoccupied by something

Other synonyms of preoccupancy include absorption, engrossment.

preoccupancy (noun)	preoccupation (noun)
the act of taking occupancy before someone else does	the act of taking occupancy before someone else does
the mental state of being preoccupied by something	the mental state of being preoccupied by something
	an idea that preoccupies the mind and holds the attention