preoccupation vs state of mind

preoccupation and state of mind both are nouns.

Word	Noun	Adjective	Verb	Adverb
preoccupation	Yes	No	No	No
state of mind	Yes	No	No	No

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

Other hypernyms of preoccupation include cognitive state.

preoccupation (noun)	state of mind (noun)
the act of taking occupancy before someone else does	the state of a person's cognitive processes
the mental state of being preoccupied by something	a temporary psychological state
an idea that preoccupies the mind and holds the attention