preoccupation vs idea

preoccupation and idea both are nouns.

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

As nouns, idea is a hypernym of preoccupation; that is, idea is a word with a broader meaning than preoccupation:

Other hypernyms of preoccupation include thought.

preoccupation (noun)	idea (noun)
the act of taking occupancy before someone else does	the content of cognition; the main thing you are thinking about
the mental state of being preoccupied by something	your intention; what you intend to do
an idea that preoccupies the mind and holds the attention	an approximate calculation of quantity or degree or worth
	a personal view
	(music) melodic subject of a musical composition